diff --git a/Elwig/Controls/IntegerUpDown.cs b/Elwig/Controls/IntegerUpDown.cs
index dba367a..fd4abd5 100644
--- a/Elwig/Controls/IntegerUpDown.cs
+++ b/Elwig/Controls/IntegerUpDown.cs
@@ -41,11 +41,19 @@ namespace Elwig.Controls {
             incButton!.Click += IncrementButton_Click;
             decButton!.Click += DecrementButton_Click;
             base.OnApplyTemplate();
+            UpdateButtons();
+        }
+
+        private void UpdateButtons() {
+            var incButton = GetTemplateChild("IncrementButton") as RepeatButton;
+            var decButton = GetTemplateChild("DecrementButton") as RepeatButton;
+            incButton?.IsEnabled = Maximum != null && Value < Maximum;
+            decButton?.IsEnabled = Minimum != null && Value > Minimum;
         }
 
         private void IntegerUpDown_TextChanged(object sender, TextChangedEventArgs evt) {
             var idx = CaretIndex;
-            Text = new string(Text.Where(char.IsAsciiDigit).Take(4).ToArray());
+            Text = new string([.. Text.Where(char.IsAsciiDigit).Take(4)]);
             CaretIndex = idx;
             evt.Handled = !(Value >= Minimum && Value <= Maximum);
             if (idx >= 4) {
@@ -56,6 +64,7 @@ namespace Elwig.Controls {
                 }
                 CaretIndex = 4;
             }
+            UpdateButtons();
         }
 
         private void IntegerUpDown_LostFocus(object sender, RoutedEventArgs evt) {
diff --git a/Elwig/Dialogs/AreaComModifyDialog.xaml.cs b/Elwig/Dialogs/AreaComModifyDialog.xaml.cs
index 0c2da99..ee064aa 100644
--- a/Elwig/Dialogs/AreaComModifyDialog.xaml.cs
+++ b/Elwig/Dialogs/AreaComModifyDialog.xaml.cs
@@ -12,23 +12,25 @@ namespace Elwig.Dialogs {
         public string OrigYearTo { get; set; }
         public string Area { get; set; }
 
-        public AreaComModifyDialog(int? yearFrom, int? yearTo, int area, bool delete) {
+        public AreaComModifyDialog(int? yearFrom, int? yearTo, int area, bool delete, bool forceRetroactive = false) {
             Area = $"{area:N0}";
             OrigYearFrom = $"{yearFrom}";
             OrigYearTo = $"{yearTo}";
             InitializeComponent();
             Title = delete ? "Flächenbindung löschen" : "Flächenbindung bearbeiten";
             RetroactiveInput.Content = delete ? "Rückwirkend löschen" : "Rückwirkend bearbeiten";
+            RetroactiveInput.IsEnabled = !forceRetroactive;
             if (delete) {
                 QuestionBlock1.Visibility = Visibility.Hidden;
                 QuestionBlock2.Visibility = Visibility.Visible;
                 DescBlock1.Visibility = Visibility.Hidden;
                 DescBlock2.Visibility = Visibility.Visible;
             }
-            if ((yearTo.HasValue && yearTo < Utils.CurrentNextSeason) || (yearFrom.HasValue && yearFrom >= Utils.CurrentNextSeason)) {
+            SeasonInput.Minimum = yearFrom + 1;
+            if (forceRetroactive || (yearTo.HasValue && yearTo < Utils.CurrentYear) || (yearFrom.HasValue && yearFrom >= Utils.CurrentYear)) {
                 RetroactiveInput.IsChecked = true;
             } else {
-                SeasonInput.Text = $"{Utils.CurrentNextSeason}";
+                SeasonInput.Text = $"{Utils.CurrentYear}";
             }
         }
 
@@ -48,7 +50,7 @@ namespace Elwig.Dialogs {
                 DescBlock2.Visibility = Visibility.Hidden;
             } else {
                 SeasonInput.IsEnabled = true;
-                SeasonInput.Text = $"{Utils.CurrentNextSeason}";
+                SeasonInput.Text = $"{Utils.CurrentYear}";
                 DescBlock1.Visibility = QuestionBlock1.Visibility;
                 DescBlock2.Visibility = QuestionBlock2.Visibility;
             }
diff --git a/Elwig/Dialogs/AreaComTransferDialog.xaml b/Elwig/Dialogs/AreaComTransferDialog.xaml
index fcec9d1..51f4f6e 100644
--- a/Elwig/Dialogs/AreaComTransferDialog.xaml
+++ b/Elwig/Dialogs/AreaComTransferDialog.xaml
@@ -8,7 +8,7 @@
         ResizeMode="NoResize" ShowInTaskbar="False" Topmost="True"
         WindowStartupLocation="CenterOwner"
         DataContext="{Binding RelativeSource={RelativeSource Self}}"
-        Title="Flächenbindungen übertragen" Height="260" Width="450">
+        Title="Flächenbindungen übertragen" Height="240" Width="450">
     <Window.Resources>
         <Style TargetType="Label">
             <Setter Property="HorizontalAlignment" Value="Left"/>
@@ -48,12 +48,8 @@
                             Minimum="1900" Maximum="9999"
                             HorizontalAlignment="Center" VerticalAlignment="Top"
                             TextChanged="SeasonInput_TextChanged"/>
-        <CheckBox x:Name="CopyYearToInput" Content="Beginn der Laufzeit von Vorgänger übernehmen" Margin="0,80,0,0"
-                  HorizontalAlignment="Center" VerticalAlignment="Top"
-                  Checked="CopyYearToInput_Changed" Unchecked="CopyYearToInput_Changed"
-                  IsChecked="{Binding MaintainYearFrom}"/>
 
-        <TextBlock x:Name="DescBlock1" Margin="0,105,0,0" TextAlignment="Center"
+        <TextBlock x:Name="DescBlock1" Margin="0,90,0,0" TextAlignment="Center"
                    HorizontalAlignment="Center" VerticalAlignment="Top">
             Die Flächenbindungen beim <Bold>Vorgänger</Bold> sind bis inkl. Saison <Bold><Run x:Name="CancelSeason1"/></Bold> gültig,<LineBreak/>
             und werden beim <Bold>Nachfolger</Bold> ab <Run x:Name="DescBlock1Season" Text="inkl. Saison "/><Bold><Run x:Name="TransferSeason"/></Bold> übernommen.
diff --git a/Elwig/Dialogs/AreaComTransferDialog.xaml.cs b/Elwig/Dialogs/AreaComTransferDialog.xaml.cs
index 9263e06..acd1d32 100644
--- a/Elwig/Dialogs/AreaComTransferDialog.xaml.cs
+++ b/Elwig/Dialogs/AreaComTransferDialog.xaml.cs
@@ -5,51 +5,51 @@ using System.Windows.Controls;
 namespace Elwig.Dialogs {
     public partial class AreaComTransferDialog : Window {
 
-        public int CancelSeason { get; set; }
-        public int SuccessorSeason => CancelSeason + 1;
-        public bool MaintainYearFrom { get; set; }
+        public int CancelSeason => SuccessorSeason - 1;
+        public int SuccessorSeason { get; set; }
 
         public string AreaComNum { get; set; }
         public string Area { get; set; }
 
         public AreaComTransferDialog(string name, int areaComNum, int area) {
-            CancelSeason = Utils.FollowingSeason - 1;
+            SuccessorSeason = Utils.FollowingSeason;
             AreaComNum = $"{areaComNum:N0}";
             Area = $"{area:N0}";
             InitializeComponent();
-            SeasonInput.Text = $"{CancelSeason}";
+            SeasonInput.Text = $"{SuccessorSeason}";
+            SeasonInput.Minimum = Utils.CurrentLastSeason;
             Title = $"Aktive Flächenbindungen kündigen - {name}";
             QuestionBlock1.Visibility = Visibility.Hidden;
             QuestionBlock2.Visibility = Visibility.Visible;
             DescBlock1.Visibility = Visibility.Hidden;
             DescBlock2.Visibility = Visibility.Visible;
-            CopyYearToInput.Visibility = Visibility.Hidden;
             Height = 240;
             SeasonInput.Margin = new(0, 40, 0, 0);
             SeasonLabel.Margin = new(0, 40, 100, 0);
         }
 
         public AreaComTransferDialog(string name, string successorName, int areaComNum, int area) {
-            CancelSeason = Utils.FollowingSeason - 1;
+            SuccessorSeason = Utils.FollowingSeason;
             AreaComNum = $"{areaComNum:N0}";
             Area = $"{area:N0}";
             InitializeComponent();
-            SeasonInput.Text = $"{CancelSeason}";
+            SeasonInput.Text = $"{SuccessorSeason}";
+            SeasonInput.Minimum = Utils.CurrentLastSeason;
             Title = $"Aktive Flächenbindungen übertragen - {name} - {successorName}";
             InfoBlock.Visibility = Visibility.Hidden;
         }
 
         private void SeasonInput_TextChanged(object sender, TextChangedEventArgs evt) {
-            CancelSeason = (int)SeasonInput.Value!;
+            SuccessorSeason = (int)SeasonInput.Value!;
             CancelSeason1.Text = $"{CancelSeason}";
             CancelSeason2.Text = $"{CancelSeason}";
-            TransferSeason.Text = MaintainYearFrom ? "" : $"{SuccessorSeason}";
-            DescBlock1Season.Text = MaintainYearFrom ? "dem originalen Beginn der FB" : "inkl. Saison ";
+            TransferSeason.Text = $"{SuccessorSeason}";
+            DescBlock1Season.Text = "inkl. Saison ";
         }
 
         private void CopyYearToInput_Changed(object sender, RoutedEventArgs evt) {
-            TransferSeason.Text = MaintainYearFrom ? "" : $"{SuccessorSeason}";
-            DescBlock1Season.Text = MaintainYearFrom ? "dem originalen Beginn der FB" : "inkl. Saison ";
+            TransferSeason.Text = $"{SuccessorSeason}";
+            DescBlock1Season.Text = "inkl. Saison ";
         }
 
         private void ConfirmButton_Click(object sender, RoutedEventArgs evt) {
diff --git a/Elwig/Documents/MemberDataSheet.cs b/Elwig/Documents/MemberDataSheet.cs
index 1793287..50a63e5 100644
--- a/Elwig/Documents/MemberDataSheet.cs
+++ b/Elwig/Documents/MemberDataSheet.cs
@@ -19,7 +19,8 @@ namespace Elwig.Documents {
         public Dictionary<string, MemberBucket> MemberBuckets;
         public List<AreaCom> ActiveAreaCommitments;
 
-        public MemberDataSheet(Member m, AppDbContext ctx) : base($"{Name} {m.AdministrativeName}", m) {
+        public MemberDataSheet(Member m, AppDbContext ctx) :
+            base($"{Name} {m.AdministrativeName}", m) {
             DocumentId = $"{Name} {m.MgNr}";
             Season = ctx.Seasons.ToList().MaxBy(s => s.Year) ?? throw new ArgumentException("invalid season");
             MemberBuckets = ctx.GetMemberBuckets(Utils.CurrentYear, m.MgNr).GetAwaiter().GetResult();
@@ -136,7 +137,7 @@ namespace Elwig.Documents {
         protected Table NewAreaComTable() {
             var areaComs = ActiveAreaCommitments.GroupBy(a => a.AreaComType).Select(group => new {
                 Type = group.Key,
-                AreaComs = group.OrderBy(c => c.Kg.AtKg.Name).ToList(),
+                AreaComs = group.OrderBy(c => c.Contract.Kg.AtKg.Name).ToList(),
                 Size = group.Sum(c => c.Area)
             }).OrderByDescending(a => a.Size).ToList();
 
@@ -164,12 +165,13 @@ namespace Elwig.Documents {
                         .SetBorderTop(contractType.Type.DisplayName != lastContract && lastContract != "" ? new SolidBorder(BorderThickness) : Border.NO_BORDER));
 
                 foreach (var areaCom in contractType.AreaComs) {
-                    tbl.AddCell(NewTd(new KernedParagraph(10).Add(Normal($"{areaCom.Kg.AtKg.Name} ")).Add(Normal($"({areaCom.Kg.AtKg.KgNr:00000})", 8))))
-                        .AddCell(NewTd(areaCom.Rd?.Name))
+                    var c = areaCom.Contract;
+                    tbl.AddCell(NewTd(new KernedParagraph(10).Add(Normal($"{c.Kg.AtKg.Name} ")).Add(Normal($"({c.Kg.AtKg.KgNr:00000})", 8))))
+                        .AddCell(NewTd(c.Rd?.Name))
                         .AddCell(NewTd(Regex.Replace(areaCom.GstNr.Replace(",", ", ").Replace("-", "\u2013"), @"\s+", " "), 10))
                         .AddCell(NewTd($"{areaCom.Area:N0}", right: true))
                         .AddCell(NewTd(areaCom.WineCult?.Name, center: true))
-                        .AddCell(NewTd(areaCom.YearTo == null ? (areaCom.YearFrom == null ? "unbefristet" : $"ab {areaCom.YearFrom}") : (areaCom.YearFrom == null ? $"bis {areaCom.YearTo}" : $"{areaCom.YearFrom}–{areaCom.YearTo}"), center: true));
+                        .AddCell(NewTd(c.YearTo == null ? (c.YearFrom == null ? "unbefristet" : $"ab {c.YearFrom}") : (c.YearFrom == null ? $"bis {c.YearTo}" : $"{c.YearFrom}–{c.YearTo}"), center: true));
                     lastContract = contractType.Type.DisplayName;
                 }
             }
diff --git a/Elwig/Helpers/AppDbContext.cs b/Elwig/Helpers/AppDbContext.cs
index 3489590..6006449 100644
--- a/Elwig/Helpers/AppDbContext.cs
+++ b/Elwig/Helpers/AppDbContext.cs
@@ -1,16 +1,16 @@
-using Microsoft.EntityFrameworkCore;
-using Elwig.Models.Entities;
-using System.Linq;
-using System.Threading.Tasks;
-using System.IO;
-using System;
-using System.Windows;
-using Microsoft.Extensions.Logging;
-using Microsoft.Data.Sqlite;
-using System.Text.RegularExpressions;
-using System.Collections.Generic;
 using Elwig.Models.Dtos;
+using Elwig.Models.Entities;
+using Microsoft.Data.Sqlite;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using System;
+using System.Collections.Generic;
 using System.Data;
+using System.IO;
+using System.Linq;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+using System.Windows;
 
 namespace Elwig.Helpers {
 
@@ -48,6 +48,7 @@ namespace Elwig.Helpers {
         public DbSet<MemberTelNr> MemberTelephoneNrs { get; private set; }
         public DbSet<MemberEmailAddr> MemberEmailAddrs { get; private set; }
         public DbSet<MemberHistory> MemberHistory { get; private set; }
+        public DbSet<AreaComContract> AreaCommitmentContracts { get; private set; }
         public DbSet<AreaCom> AreaCommitments { get; private set; }
         public DbSet<Season> Seasons { get; private set; }
         public DbSet<DeliverySchedule> DeliverySchedules { get; private set; }
@@ -142,7 +143,7 @@ namespace Elwig.Helpers {
         }
 
         public async Task<bool> FbNrExists(int fbnr) {
-            return await AreaCommitments.FindAsync(fbnr) != null;
+            return await AreaCommitmentContracts.FindAsync(fbnr) != null;
         }
 
         public async Task<bool> SortIdExists(string sortId) {
@@ -166,11 +167,18 @@ namespace Elwig.Helpers {
 
         public async Task<int> NextFbNr() {
             int c = 0;
-            (await AreaCommitments.OrderBy(ac => ac.FbNr).Select(ac => ac.FbNr).ToListAsync())
+            (await AreaCommitmentContracts.OrderBy(ac => ac.FbNr).Select(ac => ac.FbNr).ToListAsync())
                 .ForEach(a => { if (a <= c + 10000) c = a; });
             return c + 1;
         }
 
+        public async Task<int> NextRevNr(int fbnr) {
+            int c = 0;
+            (await AreaCommitments.Where(c => c.FbNr == fbnr).Select(c => c.RevNr).ToListAsync())
+                .ForEach(a => { if (a <= c + 100) c = a; });
+            return c + 1;
+        }
+
         public async Task<int> NextLNr(DateOnly date, string zwstid) {
             var dateStr = date.ToString("yyyy-MM-dd");
             int c = 0;
diff --git a/Elwig/Helpers/AppDbUpdater.cs b/Elwig/Helpers/AppDbUpdater.cs
index 6933870..2423004 100644
--- a/Elwig/Helpers/AppDbUpdater.cs
+++ b/Elwig/Helpers/AppDbUpdater.cs
@@ -9,7 +9,7 @@ namespace Elwig.Helpers {
     public static class AppDbUpdater {
 
         // Don't forget to update value in Tests/fetch-resources.bat!
-        public static readonly int RequiredSchemaVersion = 37;
+        public static readonly int RequiredSchemaVersion = 38;
 
         private static int VersionOffset = 0;
 
diff --git a/Elwig/Helpers/Export/ElwigData.cs b/Elwig/Helpers/Export/ElwigData.cs
index 8480ca3..552b5cf 100644
--- a/Elwig/Helpers/Export/ElwigData.cs
+++ b/Elwig/Helpers/Export/ElwigData.cs
@@ -60,13 +60,14 @@ namespace Elwig.Helpers.Export {
                     List<MemberTelNr> TelephoneNumbers,
                     List<MemberEmailAddr> EmailAddresses,
                     List<AreaCom> AreaCommitments,
+                    List<AreaComContract> Contracts,
                     List<WbRd> Riede,
                     List<WbKg> WbKgs,
                     List<WbGl> WbGls,
                     List<Delivery> Deliveries,
                     List<DeliveryPart> DeliveryParts,
                     List<DeliveryPartModifier> Modifiers,
-                    Dictionary<string, List<(int Id1, int Id2, DateTime CreatedAt, DateTime ModifiedAt)>> Timestamps)>();
+                    Dictionary<string, List<(int Id1, int Id2, int Id3, DateTime CreatedAt, DateTime ModifiedAt)>> Timestamps)>();
 
                 var metaData = new List<(string FileName, string ZwstId, string Device,
                     int? MemberNum, string? MemberFilters,
@@ -75,10 +76,12 @@ namespace Elwig.Helpers.Export {
 
                 foreach (var filename in filenames) {
                     try {
-                        data.Add(new([], [], [], [], [], [], [], new([], [], [], [], new() {
+                        data.Add(new([], [], [], [], [], [], [], new([], [], [], [], [], new() {
                             ["member"] = [],
+                            ["area_commitment_contract"] = [],
                             ["area_commitment"] = [],
                             ["delivery"] = [],
+                            ["delivery_part"] = [],
                         })));
                         var r = data[^1];
 
@@ -86,9 +89,11 @@ namespace Elwig.Helpers.Export {
                         using var zip = ZipFile.Open(filename, ZipArchiveMode.Read);
                         await zip.CheckIntegrity();
 
+                        string[] acceptableVersions = ["1", "2"];
                         var version = zip.GetEntry("version");
                         using (var reader = new StreamReader(version!.Open(), Utils.UTF8)) {
-                            if (await reader.ReadToEndAsync() != "elwig:1")
+                            var v = await reader.ReadToEndAsync();
+                            if (!v.StartsWith("elwig:") || !acceptableVersions.Contains(v[6..]))
                                 throw new FileFormatException($"Ungültige Elwig-Export-Datei ({filename})");
                         }
 
@@ -96,8 +101,8 @@ namespace Elwig.Helpers.Export {
                         var meta = await JsonNode.ParseAsync(metaJson!.Open());
                         var memberCount = meta!["members"]?["count"]?.AsValue().GetValue<int>();
                         var memberFilters = meta!["members"]?["filters"]?.AsArray().Select(f => f!.AsValue().GetValue<string>()).ToArray();
-                        var areaComCount = meta!["area_commitments"]?["count"]?.AsValue().GetValue<int>();
-                        var areaComFilters = meta!["area_commitments"]?["filters"]?.AsArray().Select(f => f!.AsValue().GetValue<string>()).ToArray();
+                        var areaComCount = meta!["area_commitment_contracts"]?["count"]?.AsValue().GetValue<int>();
+                        var areaComFilters = meta!["area_commitment_contracts"]?["filters"]?.AsArray().Select(f => f!.AsValue().GetValue<string>()).ToArray();
                         var deliveryCount = meta!["deliveries"]?["count"]?.AsValue().GetValue<int>();
                         var deliveryFilters = meta!["deliveries"]?["filters"]?.AsArray().Select(f => f!.AsValue().GetValue<string>()).ToArray();
                         metaData.Add((Path.GetFileName(filename),
@@ -133,23 +138,48 @@ namespace Elwig.Helpers.Export {
                                 r.TelephoneNumbers.AddRange(telNrs);
                                 r.EmailAddresses.AddRange(emailAddrs);
                                 if (timestamps.HasValue)
-                                    r.Timestamps["member"].Add((m.MgNr, 0, timestamps.Value.CreatedAt, timestamps.Value.ModifiedAt));
+                                    r.Timestamps["member"].Add((m.MgNr, 0, 0, timestamps.Value.CreatedAt, timestamps.Value.ModifiedAt));
                             }
                         }
 
+                        // legacy area commitments
                         var areaComsJson = zip.GetEntry("area_commitments.json");
                         if (areaComsJson != null) {
                             using var reader = new StreamReader(areaComsJson.Open(), Utils.UTF8);
                             string? line;
                             while ((line = await reader.ReadLineAsync()) != null) {
                                 var obj = JsonNode.Parse(line)!.AsObject();
-                                var (areaCom, wbrd, timestamps) = obj.ToAreaCom(currentWbRde);
+                                var (contract, areaCom, wbrd, timestamps) = obj.ToAreaCom(currentWbRde);
+                                r.Contracts.Add(contract);
                                 r.AreaCommitments.Add(areaCom);
                                 if (wbrd != null) {
                                     r.Riede.Add(wbrd);
                                 }
+                                if (timestamps.HasValue) {
+                                    r.Timestamps["area_commitment_contract"].Add((contract.FbNr, 0, 0, timestamps.Value.CreatedAt, timestamps.Value.ModifiedAt));
+                                    r.Timestamps["area_commitment"].Add((areaCom.FbNr, areaCom.RevNr, 0, timestamps.Value.CreatedAt, timestamps.Value.ModifiedAt));
+                                }
+                            }
+                        }
+
+                        var contractsJson = zip.GetEntry("area_commitment_contracts.json");
+                        if (contractsJson != null) {
+                            using var reader = new StreamReader(contractsJson.Open(), Utils.UTF8);
+                            string? line;
+                            while ((line = await reader.ReadLineAsync()) != null) {
+                                var obj = JsonNode.Parse(line)!.AsObject();
+                                var (contract, areaComs, wbrd, timestamps) = obj.ToAreaComContract(currentWbRde);
+                                r.Contracts.Add(contract);
+                                r.AreaCommitments.AddRange(areaComs.Select(v => v.Item1));
+                                if (wbrd != null) {
+                                    r.Riede.Add(wbrd);
+                                }
                                 if (timestamps.HasValue)
-                                    r.Timestamps["area_commitment"].Add((areaCom.FbNr, 0, timestamps.Value.CreatedAt, timestamps.Value.ModifiedAt));
+                                    r.Timestamps["area_commitment_contract"].Add((contract.FbNr, 0, 0, timestamps.Value.CreatedAt, timestamps.Value.ModifiedAt));
+                                foreach (var (areaCom, ts) in areaComs) {
+                                    if (!ts.HasValue) continue;
+                                    r.Timestamps["area_commitment"].Add((areaCom.FbNr, areaCom.RevNr, 0, ts.Value.CreatedAt, ts.Value.ModifiedAt));
+                                }
                             }
                         }
 
@@ -161,11 +191,15 @@ namespace Elwig.Helpers.Export {
                                 var obj = JsonNode.Parse(line)!.AsObject();
                                 var (d, parts, mods, rde, timestamps) = obj.ToDelivery(currentLsNrs, currentDids, kgs, currentWbRde);
                                 r.Deliveries.Add(d);
-                                r.DeliveryParts.AddRange(parts);
+                                r.DeliveryParts.AddRange(parts.Select(p => p.Item1));
                                 r.Modifiers.AddRange(mods);
                                 r.Riede.AddRange(rde);
                                 if (timestamps.HasValue)
-                                    r.Timestamps["delivery"].Add((d.Year, d.DId, timestamps.Value.CreatedAt, timestamps.Value.ModifiedAt));
+                                    r.Timestamps["delivery"].Add((d.Year, d.DId, 0, timestamps.Value.CreatedAt, timestamps.Value.ModifiedAt));
+                                foreach (var (part, ts) in parts) {
+                                    if (!ts.HasValue) continue;
+                                    r.Timestamps["area_commitment"].Add((part.Year, part.DId, part.DPNr, ts.Value.CreatedAt, ts.Value.ModifiedAt));
+                                }
                             }
                         }
                     } catch (Exception exc) when (
@@ -189,11 +223,11 @@ namespace Elwig.Helpers.Export {
                     }
                 }
 
-                var importedMembers = new List<(string FileName, string ZwstId, string Device, int New, int Overwritten, int NotImported, string Filters)>();
-                var importedAreaComs = new List<(string FileName, string ZwstId, string Device, int Imported, int NotImported, string Filters)>();
-                var importedDeliveries = new List<(string FileName, string ZwstId, string Device, int New, int Overwritten, int NotImported, string Filters)>();
+                var importedMembers = new List<(string FileName, string ZwstId, string Device, int New, int Overwritten, int NotImported, string? Filters)>();
+                var importedAreaComs = new List<(string FileName, string ZwstId, string Device, int Imported, int NotImported, string? Filters)>();
+                var importedDeliveries = new List<(string FileName, string ZwstId, string Device, int New, int Overwritten, int NotImported, string? Filters)>();
 
-                foreach (var ((members, billingAddresses, telephoneNumbers, emailAddresses, areaCommitments, riede, wbKgs, wbGls, deliveries, deliveryParts, modifiers, timestamps), meta) in data.Zip(metaData)) {
+                foreach (var ((members, billingAddresses, telephoneNumbers, emailAddresses, areaCommitments, contracts, riede, wbKgs, wbGls, deliveries, deliveryParts, modifiers, timestamps), meta) in data.Zip(metaData)) {
                     var branch = branches[meta.ZwstId];
                     var device = meta.Device;
 
@@ -220,11 +254,20 @@ namespace Elwig.Helpers.Export {
                     if (duplicateMgNrs.Count > 0)
                         importDuplicateMembers = ImportQuestion(branch.Name, device, "Mitglieder", true, duplicateMgNrs.Count);
 
-                    var fbnrs = areaCommitments.Select(c => c.FbNr).ToList();
-                    var duplicateFbNrs = await ctx.AreaCommitments
+                    var fbnrs = contracts.Select(c => c.FbNr).ToList();
+                    var duplicateFbNrs = await ctx.AreaCommitmentContracts
                         .Where(c => fbnrs.Contains(c.FbNr))
                         .Select(c => c.FbNr)
                         .ToListAsync();
+                    bool importNewContracts = false, importDuplicateContracts = false;
+                    if (mode == ImportMode.Interactively) {
+                        if (fbnrs.Count - duplicateFbNrs.Count > 0)
+                            importNewContracts = ImportQuestion(branch.Name, device, "Flächenbindungsverträge", false, fbnrs.Count - duplicateFbNrs.Count);
+                    } else {
+                        importNewContracts = true;
+                    }
+                    if (duplicateFbNrs.Count > 0)
+                        importDuplicateContracts = ImportQuestion(branch.Name, device, "Flächenbindungsverträge", true, duplicateFbNrs.Count);
 
                     var lsnrs = deliveries.Select(d => d.LsNr).ToList();
                     var duplicateLsNrs = await ctx.Deliveries
@@ -258,7 +301,7 @@ namespace Elwig.Helpers.Export {
                             importDuplicateDeliveries = ImportQuestion(branch.Name, device, "Lieferungen", true, duplicateLsNrs.Count);
                     }
 
-                    if (importDuplicateMembers || importNewMembers || importDuplicateDeliveries || importNewDeliveries) {
+                    if (importDuplicateMembers || importNewMembers || importDuplicateContracts || importNewContracts || importDuplicateDeliveries || importNewDeliveries) {
                         ctx.AddRange(wbGls);
                         ctx.UpdateRange(wbKgs.Where(k => duplicateKgNrs.Contains(k.KgNr)));
                         ctx.AddRange(wbKgs.Where(k => !duplicateKgNrs.Contains(k.KgNr)));
@@ -272,25 +315,31 @@ namespace Elwig.Helpers.Export {
                         ctx.AddRange(billingAddresses.Where(a => duplicateMgNrs.Contains(a.MgNr)));
                         ctx.AddRange(telephoneNumbers.Where(n => duplicateMgNrs.Contains(n.MgNr)));
                         ctx.AddRange(emailAddresses.Where(a => duplicateMgNrs.Contains(a.MgNr)));
-                        ctx.UpdateRange(areaCommitments.Where(c => duplicateMgNrs.Contains(c.MgNr) && duplicateFbNrs.Contains(c.FbNr)));
-                        ctx.AddRange(areaCommitments.Where(c => duplicateMgNrs.Contains(c.MgNr) && !duplicateFbNrs.Contains(c.FbNr)));
                     }
                     if (importNewMembers) {
                         ctx.AddRange(members.Where(m => !duplicateMgNrs.Contains(m.MgNr)));
                         ctx.AddRange(billingAddresses.Where(a => !duplicateMgNrs.Contains(a.MgNr)));
                         ctx.AddRange(telephoneNumbers.Where(n => !duplicateMgNrs.Contains(n.MgNr)));
                         ctx.AddRange(emailAddresses.Where(a => !duplicateMgNrs.Contains(a.MgNr)));
-                        ctx.UpdateRange(areaCommitments.Where(c => !duplicateMgNrs.Contains(c.MgNr) && duplicateFbNrs.Contains(c.FbNr)));
-                        ctx.AddRange(areaCommitments.Where(c => !duplicateMgNrs.Contains(c.MgNr) && !duplicateFbNrs.Contains(c.FbNr)));
                     }
                     if (members.Count > 0) {
                         var n = importNewMembers ? members.Count - duplicateMgNrs.Count : 0;
                         var o = importDuplicateMembers ? duplicateMgNrs.Count : 0;
                         importedMembers.Add((meta.FileName, meta.ZwstId, meta.Device, n, o, members.Count - n - o, meta.MemberFilters));
                     }
-                    if (areaCommitments.Count > 0) {
+
+                    if (importDuplicateContracts) {
+                        ctx.RemoveRange(ctx.AreaCommitments.Where(c => duplicateFbNrs.Contains(c.FbNr)));
+                        ctx.UpdateRange(contracts.Where(c => duplicateFbNrs.Contains(c.FbNr)));
+                        ctx.AddRange(areaCommitments.Where(c => duplicateFbNrs.Contains(c.FbNr)));
+                    }
+                    if (importNewContracts) {
+                        ctx.AddRange(contracts.Where(c => !duplicateFbNrs.Contains(c.FbNr)));
+                        ctx.AddRange(areaCommitments.Where(c => !duplicateFbNrs.Contains(c.FbNr)));
+                    }
+                    if (contracts.Count > 0) {
                         ctx.AddRange(riede);
-                        var imported = areaCommitments.Where(c => (importNewMembers && !duplicateMgNrs.Contains(c.MgNr)) || (importDuplicateMembers && duplicateMgNrs.Contains(c.MgNr))).ToList();
+                        var imported = contracts.Where(c => (importNewContracts && !duplicateFbNrs.Contains(c.FbNr)) || (importDuplicateContracts && duplicateFbNrs.Contains(c.FbNr))).ToList();
                         importedAreaComs.Add((meta.FileName, meta.ZwstId, meta.Device, imported.Count, areaCommitments.Count - imported.Count, meta.AreaComFilters));
                     }
 
@@ -335,15 +384,17 @@ namespace Elwig.Helpers.Export {
                     await ctx.SaveChangesAsync();
 
                     var primaryKeys = new Dictionary<string, string>() {
-                        ["member"] = "mgnr, 0",
-                        ["area_commitment"] = "fbnr, 0",
-                        ["delivery"] = "year, did",
+                        ["member"] = "mgnr, 0, 0",
+                        ["area_commitment_contract"] = "fbnr, 0, 0",
+                        ["area_commitment"] = "fbnr, revnr, 0",
+                        ["delivery"] = "year, did, 0",
+                        ["delivery_part"] = "year, did, dpnr",
                     };
                     var updateStmts = timestamps
                         .SelectMany(e => e.Value.Select(m => $"UPDATE {e.Key} " +
                                                              $"SET ctime = {((DateTimeOffset)m.CreatedAt.ToUniversalTime()).ToUnixTimeSeconds()}, " +
                                                                  $"mtime = {((DateTimeOffset)m.ModifiedAt.ToUniversalTime()).ToUnixTimeSeconds()} " +
-                                                             $"WHERE ({primaryKeys[e.Key]}) = ({m.Id1}, {m.Id2});"));
+                                                             $"WHERE ({primaryKeys[e.Key]}) = ({m.Id1}, {m.Id2}, {m.Id3});"));
                     using var cnx = AppDbContext.Connect();
                     await cnx.ExecuteBatch($"""
                         BEGIN;
@@ -407,7 +458,7 @@ namespace Elwig.Helpers.Export {
             }.Export(filename);
         }
 
-        public static Task Export(string filename, IEnumerable<Member> members, IEnumerable<AreaCom> areaComs, IEnumerable<WbKg> wbKgs, IEnumerable<string> filters) {
+        public static Task Export(string filename, IEnumerable<Member> members, IEnumerable<AreaComContract> areaComs, IEnumerable<WbKg> wbKgs, IEnumerable<string> filters) {
             return new ElwigExport {
                 Members = (members, filters),
                 AreaComs = (areaComs, ["von exportierten Mitgliedern"]),
@@ -425,7 +476,7 @@ namespace Elwig.Helpers.Export {
         public class ElwigExport {
             public (IEnumerable<WbKg> WbKgs, IEnumerable<string> Filters)? WbKgs { get; set; }
             public (IEnumerable<Member> Members, IEnumerable<string> Filters)? Members { get; set; }
-            public (IEnumerable<AreaCom> AreaComs, IEnumerable<string> Filters)? AreaComs { get; set; }
+            public (IEnumerable<AreaComContract> AreaComs, IEnumerable<string> Filters)? AreaComs { get; set; }
             public (IEnumerable<Delivery> Deliveries, IEnumerable<string> Filters)? Deliveries { get; set; }
 
             public async Task Export(string filename) {
@@ -434,7 +485,7 @@ namespace Elwig.Helpers.Export {
 
                 var version = zip.CreateEntry("version", CompressionLevel.NoCompression);
                 using (var writer = new StreamWriter(version.Open(), Utils.UTF8)) {
-                    await writer.WriteAsync("elwig:1");
+                    await writer.WriteAsync("elwig:2");
                 }
 
                 var meta = zip.CreateEntry("meta.json", CompressionLevel.NoCompression);
@@ -456,8 +507,9 @@ namespace Elwig.Helpers.Export {
                             ["filters"] = new JsonArray(Members.Value.Filters.Select(f => (JsonNode)f).ToArray()),
                         };
                     if (AreaComs != null)
-                        obj["area_commitments"] = new JsonObject {
+                        obj["area_commitment_contracts"] = new JsonObject {
                             ["count"] = AreaComs.Value.AreaComs.Count(),
+                            ["revisions"] = AreaComs.Value.AreaComs.Sum(c => c.Revisions.Count),
                             ["filters"] = new JsonArray(AreaComs.Value.Filters.Select(f => (JsonNode)f).ToArray()),
                         };
                     if (Deliveries != null)
@@ -485,7 +537,7 @@ namespace Elwig.Helpers.Export {
                     }
                 }
                 if (AreaComs != null) {
-                    var json = zip.CreateEntry("area_commitments.json", CompressionLevel.SmallestSize);
+                    var json = zip.CreateEntry("area_commitment_contracts.json", CompressionLevel.SmallestSize);
                     using var writer = new StreamWriter(json.Open(), Utils.UTF8);
                     foreach (var c in AreaComs.Value.AreaComs) {
                         await writer.WriteLineAsync(c.ToJson().ToJsonString(Utils.JsonOpts));
@@ -639,42 +691,102 @@ namespace Elwig.Helpers.Export {
                 CountryNum = a["country"]!.AsValue().GetValue<int>(),
                 PostalDestId = a["postal_dest"]!.AsValue().GetValue<string>(),
                 Address = a["address"]!.AsValue().GetValue<string>(),
-            } : null, json["telephone_numbers"]!.AsArray().Select(n => n!.AsObject()).Select((n, i) => new MemberTelNr {
+            } : null, [.. json["telephone_numbers"]!.AsArray().Select(n => n!.AsObject()).Select((n, i) => new MemberTelNr {
                 MgNr = mgnr,
                 Nr = i + 1,
                 Type = n["type"]!.AsValue().GetValue<string>(),
                 Number = n["number"]!.AsValue().GetValue<string>(),
                 Comment = n["comment"]?.AsValue().GetValue<string>(),
-            }).ToList(), json["email_addresses"]!.AsArray().Select(a => a!.AsObject()).Select((a, i) => new MemberEmailAddr {
+            })], [.. json["email_addresses"]!.AsArray().Select(a => a!.AsObject()).Select((a, i) => new MemberEmailAddr {
                 MgNr = mgnr,
                 Nr = i + 1,
                 Address = a["address"]!.AsValue().GetValue<string>(),
                 Comment = a["comment"]?.AsValue().GetValue<string>(),
-            }).ToList(),
+            })],
             createdAt == null || modifiedAt == null ? null :
             (DateTime.ParseExact(createdAt, "yyyy-MM-ddTHH:mm:ssK", CultureInfo.InvariantCulture, DateTimeStyles.None),
              DateTime.ParseExact(modifiedAt, "yyyy-MM-ddTHH:mm:ssK", CultureInfo.InvariantCulture, DateTimeStyles.None)));
         }
 
-        public static JsonObject ToJson(this AreaCom c) {
+        public static JsonObject ToJson(this AreaComContract c) {
             return new JsonObject {
                 ["fbnr"] = c.FbNr,
-                ["mgnr"] = c.MgNr,
-                ["vtrgid"] = c.VtrgId,
-                ["cultid"] = c.CultId,
-                ["area"] = c.Area,
                 ["kgnr"] = c.KgNr,
-                ["gstnr"] = c.GstNr,
                 ["ried"] = c.Rd?.Name,
-                ["year_from"] = c.YearFrom,
-                ["year_to"] = c.YearTo,
+                ["revisions"] = new JsonArray(c.Revisions.OrderBy(r => r.RevNr).Select(r => r.ToJson()).ToArray()),
                 ["comment"] = c.Comment,
                 ["created_at"] = $"{c.CreatedAt:yyyy-MM-ddTHH:mm:ssK}",
                 ["modified_at"] = $"{c.ModifiedAt:yyyy-MM-ddTHH:mm:ssK}",
             };
         }
 
-        public static (AreaCom, WbRd?, (DateTime CreatedAt, DateTime ModifiedAt)?) ToAreaCom(this JsonNode json, Dictionary<int, List<WbRd>> riede) {
+        private static JsonObject ToJson(this AreaCom c) {
+            return new JsonObject {
+                ["revnr"] = c.RevNr,
+                ["mgnr"] = c.MgNr,
+                ["vtrgid"] = c.VtrgId,
+                ["cultid"] = c.CultId,
+                ["area"] = c.Area,
+                ["gstnr"] = c.GstNr,
+                ["year_from"] = c.YearFrom,
+                ["year_to"] = c.YearTo,
+                ["created_at"] = $"{c.CreatedAt:yyyy-MM-ddTHH:mm:ssK}",
+                ["modified_at"] = $"{c.ModifiedAt:yyyy-MM-ddTHH:mm:ssK}",
+            };
+        }
+
+        public static (AreaComContract, List<(AreaCom, (DateTime CreatedAt, DateTime ModifiedAt)?)>, WbRd?, (DateTime CreatedAt, DateTime ModifiedAt)?) ToAreaComContract(this JsonNode json, Dictionary<int, List<WbRd>> riede) {
+            var kgnr = json["kgnr"]!.AsValue().GetValue<int>();
+            var ried = json["ried"]?.AsValue().GetValue<string>();
+            var fbnr = json["fbnr"]!.AsValue()!.GetValue<int>();
+            WbRd? rd = null;
+            bool newRd = false;
+            if (ried != null) {
+                var rde = riede.GetValueOrDefault(kgnr, []);
+                rd = rde.FirstOrDefault(r => r.Name == ried);
+                if (rd == null) {
+                    newRd = true;
+                    rd = new WbRd {
+                        KgNr = kgnr,
+                        RdNr = (rde.Count == 0 ? 1 : rde.Max(r => r.RdNr)) + 1,
+                        Name = ried,
+                    };
+                    rde.Add(rd);
+                    riede[rd.KgNr] = rde;
+                }
+            }
+            var createdAt = json["created_at"]?.AsValue().GetValue<string>();
+            var modifiedAt = json["modified_at"]?.AsValue().GetValue<string>();
+            return (new AreaComContract {
+                FbNr = fbnr,
+                KgNr = kgnr,
+                RdNr = rd?.RdNr ?? json["rdnr"]?.AsValue().GetValue<int>(),
+                Comment = json["comment"]?.AsValue().GetValue<string>(),
+                ImportedAt = DateTime.Now,
+            }, [.. json["revisions"]!.AsArray().Select(r => r!.AsObject()).Select<JsonObject, (AreaCom, (DateTime, DateTime)?)>(r => {
+                var createdAt = json["created_at"]?.AsValue().GetValue<string>();
+                var modifiedAt = json["modified_at"]?.AsValue().GetValue<string>();
+                return (new AreaCom {
+                    FbNr = fbnr,
+                    RevNr = r["revnr"]!.AsValue().GetValue<int>(),
+                    MgNr = r["mgnr"]!.AsValue().GetValue<int>(),
+                    VtrgId = r["vtrgid"]!.AsValue().GetValue<string>(),
+                    CultId = r["cultid"]?.AsValue().GetValue<string>(),
+                    Area = r["area"]!.AsValue().GetValue<int>(),
+                    GstNr = r["gstnr"]?.AsValue().GetValue<string>() ?? "-",
+                    YearFrom = r["year_from"]?.AsValue().GetValue<int>(),
+                    YearTo = r["year_to"]?.AsValue().GetValue<int>(),
+                    ImportedAt = DateTime.Now,
+                }, createdAt == null || modifiedAt == null ? null :
+                (DateTime.ParseExact(createdAt, "yyyy-MM-ddTHH:mm:ssK", CultureInfo.InvariantCulture, DateTimeStyles.None),
+                 DateTime.ParseExact(modifiedAt, "yyyy-MM-ddTHH:mm:ssK", CultureInfo.InvariantCulture, DateTimeStyles.None)));
+            })], newRd ? rd : null,
+            createdAt == null || modifiedAt == null ? null :
+            (DateTime.ParseExact(createdAt, "yyyy-MM-ddTHH:mm:ssK", CultureInfo.InvariantCulture, DateTimeStyles.None),
+             DateTime.ParseExact(modifiedAt, "yyyy-MM-ddTHH:mm:ssK", CultureInfo.InvariantCulture, DateTimeStyles.None)));
+        }
+
+        public static (AreaComContract, AreaCom, WbRd?, (DateTime CreatedAt, DateTime ModifiedAt)?) ToAreaCom(this JsonNode json, Dictionary<int, List<WbRd>> riede) {
             var kgnr = json["kgnr"]!.AsValue().GetValue<int>();
             var ried = json["ried"]?.AsValue().GetValue<string>();
             WbRd? rd = null;
@@ -695,18 +807,22 @@ namespace Elwig.Helpers.Export {
             }
             var createdAt = json["created_at"]?.AsValue().GetValue<string>();
             var modifiedAt = json["modified_at"]?.AsValue().GetValue<string>();
-            return (new AreaCom {
+            return (new AreaComContract {
                 FbNr = json["fbnr"]!.AsValue().GetValue<int>(),
+                KgNr = kgnr,
+                RdNr = rd?.RdNr ?? json["rdnr"]?.AsValue().GetValue<int>(),
+                Comment = json["comment"]?.AsValue().GetValue<string>(),
+                ImportedAt = DateTime.Now,
+            }, new AreaCom {
+                FbNr = json["fbnr"]!.AsValue().GetValue<int>(),
+                RevNr = 1,
                 MgNr = json["mgnr"]!.AsValue().GetValue<int>(),
                 VtrgId = json["vtrgid"]!.AsValue().GetValue<string>(),
                 CultId = json["cultid"]?.AsValue().GetValue<string>(),
                 Area = json["area"]!.AsValue().GetValue<int>(),
-                KgNr = kgnr,
                 GstNr = json["gstnr"]?.AsValue().GetValue<string>() ?? "-",
-                RdNr = rd?.RdNr ?? json["rdnr"]?.AsValue().GetValue<int>(),
                 YearFrom = json["year_from"]?.AsValue().GetValue<int>(),
                 YearTo = json["year_to"]?.AsValue().GetValue<int>(),
-                Comment = json["comment"]?.AsValue().GetValue<string>(),
                 ImportedAt = DateTime.Now,
             }, newRd ? rd : null,
             createdAt == null || modifiedAt == null ? null :
@@ -723,43 +839,45 @@ namespace Elwig.Helpers.Export {
                 ["lnr"] = d.LNr,
                 ["time"] = d.Time != null ? $"{d.Time:HH:mm:ss}" : null,
                 ["mgnr"] = d.MgNr,
-                ["parts"] = new JsonArray(d.Parts.OrderBy(p => p.DPNr).Select(p => {
-                    var obj = new JsonObject {
-                        ["dpnr"] = p.DPNr,
-                        ["sortid"] = p.SortId,
-                        ["attrid"] = p.AttrId,
-                        ["cultid"] = p.CultId,
-                        ["weight"] = p.Weight,
-                        ["kmw"] = p.Kmw,
-                        ["qualid"] = p.QualId,
-                        ["hkid"] = p.HkId,
-                        ["kgnr"] = p.KgNr,
-                        ["ried"] = p.Rd?.Name,
-                        ["net_weight"] = p.IsNetWeight,
-                        ["manual_weighing"] = p.IsManualWeighing,
-                        ["modids"] = new JsonArray(p.Modifiers.Select(m => (JsonNode)m.ModId).ToArray()),
-                        ["comment"] = p.Comment,
-                        ["created_at"] = $"{p.CreatedAt:yyyy-MM-ddTHH:mm:ssK}",
-                        ["modified_at"] = $"{p.ModifiedAt:yyyy-MM-ddTHH:mm:ssK}",
-                    };
-                    if (p.IsSplCheck) obj["spl_check"] = p.IsSplCheck;
-                    if (p.IsHandPicked != null) obj["hand_picked"] = p.IsHandPicked;
-                    if (p.IsGebunden != null) obj["gebunden"] = p.IsGebunden;
-                    if (p.Unloading != null) obj["unloading"] = p.Unloading;
-                    if (p.Temperature != null) obj["temperature"] = p.Temperature;
-                    if (p.Acid != null) obj["acid"] = p.Acid;
-                    if (p.ScaleId != null) obj["scale_id"] = p.ScaleId;
-                    if (p.WeighingData != null) obj["weighing_data"] = JsonNode.Parse(p.WeighingData);
-                    if (p.WeighingReason != null) obj["weighing_reason"] = p.WeighingReason;
-                    return obj;
-                }).ToArray()),
+                ["parts"] = new JsonArray(d.Parts.OrderBy(p => p.DPNr).Select(p => p.ToJson()).ToArray()),
                 ["comment"] = d.Comment,
                 ["created_at"] = $"{d.CreatedAt:yyyy-MM-ddTHH:mm:ssK}",
                 ["modified_at"] = $"{d.ModifiedAt:yyyy-MM-ddTHH:mm:ssK}",
             };
         }
 
-        public static (Delivery, List<DeliveryPart>, List<DeliveryPartModifier>, List<WbRd>, (DateTime CreatedAt, DateTime ModifiedAt)?) ToDelivery(this JsonNode json, Dictionary<string, int> currentLsNrs, Dictionary<int, int> currentDids, Dictionary<int, AT_Kg> kgs, Dictionary<int, List<WbRd>> riede) {
+        private static JsonObject ToJson(this DeliveryPart p) {
+            var obj = new JsonObject {
+                ["dpnr"] = p.DPNr,
+                ["sortid"] = p.SortId,
+                ["attrid"] = p.AttrId,
+                ["cultid"] = p.CultId,
+                ["weight"] = p.Weight,
+                ["kmw"] = p.Kmw,
+                ["qualid"] = p.QualId,
+                ["hkid"] = p.HkId,
+                ["kgnr"] = p.KgNr,
+                ["ried"] = p.Rd?.Name,
+                ["net_weight"] = p.IsNetWeight,
+                ["manual_weighing"] = p.IsManualWeighing,
+                ["modids"] = new JsonArray(p.Modifiers.Select(m => (JsonNode)m.ModId).ToArray()),
+                ["comment"] = p.Comment,
+                ["created_at"] = $"{p.CreatedAt:yyyy-MM-ddTHH:mm:ssK}",
+                ["modified_at"] = $"{p.ModifiedAt:yyyy-MM-ddTHH:mm:ssK}",
+            };
+            if (p.IsSplCheck) obj["spl_check"] = p.IsSplCheck;
+            if (p.IsHandPicked != null) obj["hand_picked"] = p.IsHandPicked;
+            if (p.IsGebunden != null) obj["gebunden"] = p.IsGebunden;
+            if (p.Unloading != null) obj["unloading"] = p.Unloading;
+            if (p.Temperature != null) obj["temperature"] = p.Temperature;
+            if (p.Acid != null) obj["acid"] = p.Acid;
+            if (p.ScaleId != null) obj["scale_id"] = p.ScaleId;
+            if (p.WeighingData != null) obj["weighing_data"] = JsonNode.Parse(p.WeighingData);
+            if (p.WeighingReason != null) obj["weighing_reason"] = p.WeighingReason;
+            return obj;
+        }
+
+        public static (Delivery, List<(DeliveryPart, (DateTime CreatedAt, DateTime ModifiedAt)?)>, List<DeliveryPartModifier>, List<WbRd>, (DateTime CreatedAt, DateTime ModifiedAt)?) ToDelivery(this JsonNode json, Dictionary<string, int> currentLsNrs, Dictionary<int, int> currentDids, Dictionary<int, AT_Kg> kgs, Dictionary<int, List<WbRd>> riede) {
             var year = json["year"]!.AsValue().GetValue<int>();
             var lsnr = json["lsnr"]!.AsValue().GetValue<string>();
             var did = currentLsNrs.GetValueOrDefault(lsnr, -1);
@@ -782,7 +900,7 @@ namespace Elwig.Helpers.Export {
                 MgNr = json["mgnr"]!.AsValue().GetValue<int>(),
                 Comment = json["comment"]?.AsValue().GetValue<string>(),
                 ImportedAt = DateTime.Now,
-            }, json["parts"]!.AsArray().Select(p => p!.AsObject()).Select(p => {
+            }, [.. json["parts"]!.AsArray().Select(p => p!.AsObject()).Select<JsonObject, (DeliveryPart, (DateTime, DateTime)?)>(p => {
                 var kgnr = p["kgnr"]?.AsValue().GetValue<int>();
                 var ried = p["ried"]?.AsValue().GetValue<string>();
                 WbRd? rd = null;
@@ -800,7 +918,9 @@ namespace Elwig.Helpers.Export {
                         wbRde.Add(rd);
                     }
                 }
-                return new DeliveryPart {
+                var createdAt = p["created_at"]?.AsValue().GetValue<string>();
+                var modifiedAt = p["modified_at"]?.AsValue().GetValue<string>();
+                return (new DeliveryPart {
                     Year = year,
                     DId = did,
                     DPNr = p["dpnr"]!.AsValue().GetValue<int>(),
@@ -825,13 +945,15 @@ namespace Elwig.Helpers.Export {
                     ScaleId = p["scale_id"]?.AsValue().GetValue<string>(),
                     WeighingData = p["weighing_data"]?.AsObject().ToJsonString(Utils.JsonOpts),
                     WeighingReason = p["weighing_reason"]?.AsValue().GetValue<string>(),
-                };
-            }).ToList(), json["parts"]!.AsArray().SelectMany(p => p!["modids"]!.AsArray().Select(m => new DeliveryPartModifier {
+                }, createdAt == null || modifiedAt == null ? null :
+                (DateTime.ParseExact(createdAt, "yyyy-MM-ddTHH:mm:ssK", CultureInfo.InvariantCulture, DateTimeStyles.None),
+                 DateTime.ParseExact(modifiedAt, "yyyy-MM-ddTHH:mm:ssK", CultureInfo.InvariantCulture, DateTimeStyles.None)));
+            })], [.. json["parts"]!.AsArray().SelectMany(p => p!["modids"]!.AsArray().Select(m => new DeliveryPartModifier {
                 Year = year,
                 DId = did,
                 DPNr = p["dpnr"]!.AsValue().GetValue<int>(),
                 ModId = m!.AsValue().GetValue<string>(),
-            })).ToList(),
+            }))],
             wbRde,
             createdAt == null || modifiedAt == null ? null :
             (DateTime.ParseExact(createdAt, "yyyy-MM-ddTHH:mm:ssK", CultureInfo.InvariantCulture, DateTimeStyles.None),
diff --git a/Elwig/Helpers/Validator.cs b/Elwig/Helpers/Validator.cs
index b0b76e0..72a16b5 100644
--- a/Elwig/Helpers/Validator.cs
+++ b/Elwig/Helpers/Validator.cs
@@ -580,7 +580,7 @@ namespace Elwig.Helpers {
             }
         }
 
-        public static ValidationResult CheckFbNr(TextBox input, bool required, AreaCom? c) {
+        public static ValidationResult CheckFbNr(TextBox input, bool required, AreaComContract? c) {
             var res = CheckInteger(input, required);
             if (!res.IsValid) {
                 return res;
diff --git a/Elwig/Models/Entities/AreaCom.cs b/Elwig/Models/Entities/AreaCom.cs
index 763c2e9..d049440 100644
--- a/Elwig/Models/Entities/AreaCom.cs
+++ b/Elwig/Models/Entities/AreaCom.cs
@@ -1,15 +1,16 @@
-using Elwig.Helpers;
 using Microsoft.EntityFrameworkCore;
 using System;
-using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations.Schema;
 
 namespace Elwig.Models.Entities {
-    [Table("area_commitment"), PrimaryKey("FbNr")]
+    [Table("area_commitment"), PrimaryKey("FbNr", "RevNr")]
     public class AreaCom {
         [Column("fbnr")]
         public int FbNr { get; set; }
 
+        [Column("revnr")]
+        public int RevNr { get; set; }
+
         [Column("mgnr")]
         public int MgNr { get; set; }
 
@@ -22,24 +23,15 @@ namespace Elwig.Models.Entities {
         [Column("area")]
         public int Area { get; set; }
 
-        [Column("kgnr")]
-        public int KgNr { get; set; }
-
         [Column("gstnr")]
         public required string GstNr { get; set; }
 
-        [Column("rdnr")]
-        public int? RdNr { get; set; }
-
         [Column("year_from")]
         public int? YearFrom { get; set; }
 
         [Column("year_to")]
         public int? YearTo { get; set; }
 
-        [Column("comment")]
-        public string? Comment { get; set; }
-
         [Column("ctime"), DatabaseGenerated(DatabaseGeneratedOption.Computed)]
         public long CTime { get; set; }
         [NotMapped]
@@ -72,6 +64,9 @@ namespace Elwig.Models.Entities {
             set => ITime = value == null ? null : ((DateTimeOffset)value.Value.ToUniversalTime()).ToUnixTimeSeconds();
         }
 
+        [ForeignKey("FbNr")]
+        public virtual AreaComContract Contract { get; private set; } = null!;
+
         [ForeignKey("MgNr")]
         public virtual Member Member { get; private set; } = null!;
 
@@ -80,17 +75,5 @@ namespace Elwig.Models.Entities {
 
         [ForeignKey("CultId")]
         public virtual WineCult? WineCult { get; private set; }
-
-        [ForeignKey("KgNr")]
-        public virtual WbKg Kg { get; private set; } = null!;
-
-        [ForeignKey("KgNr, RdNr")]
-        public virtual WbRd? Rd { get; private set; }
-
-        public int SearchScore(IEnumerable<string> keywords) {
-            return Utils.GetSearchScore([
-                 WineCult?.Name, Kg.AtKg.Name, Rd?.Name, GstNr, Comment,
-            ], keywords);
-        }
     }
 }
diff --git a/Elwig/Models/Entities/AreaComContract.cs b/Elwig/Models/Entities/AreaComContract.cs
new file mode 100644
index 0000000..4b5cecb
--- /dev/null
+++ b/Elwig/Models/Entities/AreaComContract.cs
@@ -0,0 +1,78 @@
+using Elwig.Helpers;
+using Microsoft.EntityFrameworkCore;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations.Schema;
+using System.Linq;
+
+namespace Elwig.Models.Entities {
+    [Table("area_commitment_contract"), PrimaryKey("FbNr")]
+    public class AreaComContract {
+        [Column("fbnr")]
+        public int FbNr { get; set; }
+
+        [Column("kgnr")]
+        public int KgNr { get; set; }
+
+        [Column("rdnr")]
+        public int? RdNr { get; set; }
+
+        [Column("comment")]
+        public string? Comment { get; set; }
+
+        [Column("ctime"), DatabaseGenerated(DatabaseGeneratedOption.Computed)]
+        public long CTime { get; set; }
+        [NotMapped]
+        public DateTime CreatedAt {
+            get => DateTimeOffset.FromUnixTimeSeconds(CTime).LocalDateTime;
+            set => CTime = ((DateTimeOffset)value.ToUniversalTime()).ToUnixTimeSeconds();
+        }
+
+        [Column("mtime"), DatabaseGenerated(DatabaseGeneratedOption.Computed)]
+        public long MTime { get; set; }
+        [NotMapped]
+        public DateTime ModifiedAt {
+            get => DateTimeOffset.FromUnixTimeSeconds(MTime).LocalDateTime;
+            set => MTime = ((DateTimeOffset)value.ToUniversalTime()).ToUnixTimeSeconds();
+        }
+
+        [Column("xtime")]
+        public long? XTime { get; set; }
+        [NotMapped]
+        public DateTime? ExportedAt {
+            get => XTime == null ? null : DateTimeOffset.FromUnixTimeSeconds(XTime.Value).LocalDateTime;
+            set => XTime = value == null ? null : ((DateTimeOffset)value.Value.ToUniversalTime()).ToUnixTimeSeconds();
+        }
+
+        [Column("itime")]
+        public long? ITime { get; set; }
+        [NotMapped]
+        public DateTime? ImportedAt {
+            get => ITime == null ? null : DateTimeOffset.FromUnixTimeSeconds(ITime.Value).LocalDateTime;
+            set => ITime = value == null ? null : ((DateTimeOffset)value.Value.ToUniversalTime()).ToUnixTimeSeconds();
+        }
+
+        [ForeignKey("KgNr")]
+        public virtual WbKg Kg { get; private set; } = null!;
+
+        [ForeignKey("KgNr, RdNr")]
+        public virtual WbRd? Rd { get; private set; }
+
+        [InverseProperty(nameof(AreaCom.Contract))]
+        public virtual ICollection<AreaCom> Revisions { get; private set; } = null!;
+
+        [NotMapped]
+        public AreaCom? Latest => Revisions.OrderBy(r => r.RevNr).LastOrDefault();
+
+        [NotMapped]
+        public int? YearFrom => Revisions.Any(r => r.YearFrom == null) ? null : Revisions.Min(r => r.YearFrom);
+        [NotMapped]
+        public int? YearTo => Revisions.Any(r => r.YearTo == null) ? null : Revisions.Max(r => r.YearTo);
+
+        public int SearchScore(IEnumerable<string> keywords) {
+            return Utils.GetSearchScore([
+                 ..Revisions.Select(r => r.WineCult?.Name), Kg.AtKg.Name, Rd?.Name, ..Revisions.Select(r => r.GstNr), Comment,
+            ], keywords);
+        }
+    }
+}
diff --git a/Elwig/Resources/Sql/37-38.sql b/Elwig/Resources/Sql/37-38.sql
new file mode 100644
index 0000000..71bce4c
--- /dev/null
+++ b/Elwig/Resources/Sql/37-38.sql
@@ -0,0 +1,218 @@
+-- schema version 37 to 38
+
+UPDATE client_parameter SET value = '0' WHERE param = 'ENABLE_TIME_TRIGGERS';
+
+DROP TRIGGER t_area_commitment_i_ctime;
+DROP TRIGGER t_area_commitment_u_ctime;
+DROP TRIGGER t_area_commitment_i_mtime;
+DROP TRIGGER t_area_commitment_u_mtime;
+
+CREATE TABLE area_commitment_contract (
+    fbnr      INTEGER NOT NULL,
+
+    kgnr      INTEGER NOT NULL,
+    rdnr      INTEGER,
+
+    comment   TEXT             DEFAULT NULL,
+    ctime     INTEGER NOT NULL DEFAULT (UNIXEPOCH()),
+    mtime     INTEGER NOT NULL DEFAULT (UNIXEPOCH()),
+    xtime     INTEGER          DEFAULT NULL,
+    itime     INTEGER          DEFAULT NULL,
+
+    CONSTRAINT area_commitment_contract PRIMARY KEY (fbnr),
+    CONSTRAINT fk_area_commitment_contract_wb_kg FOREIGN KEY (kgnr) REFERENCES wb_kg (kgnr)
+        ON UPDATE CASCADE
+        ON DELETE RESTRICT,
+    CONSTRAINT fk_area_commitment_contract_wb_rd FOREIGN KEY (kgnr, rdnr) REFERENCES wb_rd (kgnr, rdnr)
+        ON UPDATE CASCADE
+        ON DELETE RESTRICT
+) STRICT;
+
+CREATE TABLE area_commitment_new (
+    fbnr      INTEGER NOT NULL,
+    revnr     INTEGER NOT NULL,
+    mgnr      INTEGER NOT NULL,
+
+    vtrgid    TEXT    NOT NULL,
+    cultid    TEXT             DEFAULT NULL,
+    area      INTEGER NOT NULL,
+    gstnr     TEXT    NOT NULL,
+
+    year_from INTEGER CHECK (year_from >= 1000 AND year_from <= 9999) DEFAULT NULL,
+    year_to   INTEGER CHECK (year_to   >= 1000 AND year_to   <= 9999) DEFAULT NULL,
+
+    ctime     INTEGER NOT NULL DEFAULT (UNIXEPOCH()),
+    mtime     INTEGER NOT NULL DEFAULT (UNIXEPOCH()),
+    xtime     INTEGER          DEFAULT NULL,
+    itime     INTEGER          DEFAULT NULL,
+
+    CONSTRAINT pk_area_commitment PRIMARY KEY (fbnr, revnr),
+    CONSTRAINT fk_area_commitment_area_commitment_contract FOREIGN KEY (fbnr) REFERENCES area_commitment_contract (fbnr)
+        ON UPDATE CASCADE
+        ON DELETE CASCADE,
+    CONSTRAINT fk_area_commitment_member FOREIGN KEY (mgnr) REFERENCES member (mgnr)
+        ON UPDATE CASCADE
+        ON DELETE RESTRICT,
+    CONSTRAINT fk_area_commitment_area_commitment_type FOREIGN KEY (vtrgid) REFERENCES area_commitment_type (vtrgid)
+        ON UPDATE CASCADE
+        ON DELETE RESTRICT,
+    CONSTRAINT fk_area_commitment_wine_cultivation FOREIGN KEY (cultid) REFERENCES wine_cultivation (cultid)
+        ON UPDATE CASCADE
+        ON DELETE RESTRICT
+) STRICT;
+
+INSERT INTO area_commitment_contract (fbnr, kgnr, rdnr, comment, ctime, mtime, xtime, itime)
+SELECT fbnr, kgnr, rdnr, comment, ctime, mtime, xtime, itime
+FROM area_commitment;
+
+INSERT INTO area_commitment_new (fbnr, revnr, mgnr, vtrgid, cultid, area, gstnr, year_from, year_to, ctime, mtime, xtime, itime)
+SELECT fbnr, 1, mgnr, vtrgid, cultid, area, gstnr, year_from, year_to, ctime, mtime, xtime, itime
+FROM area_commitment;
+
+PRAGMA foreign_keys = OFF;
+PRAGMA writable_schema = ON;
+DROP TABLE area_commitment;
+ALTER TABLE area_commitment_new RENAME TO area_commitment;
+PRAGMA writable_schema = OFF;
+PRAGMA foreign_keys = ON;
+
+CREATE TRIGGER t_area_commitment_contract_i_ctime
+    AFTER INSERT ON area_commitment_contract FOR EACH ROW
+    WHEN (SELECT value FROM client_parameter WHERE param = 'ENABLE_TIME_TRIGGERS') = 1 AND NEW.ctime != UNIXEPOCH()
+BEGIN
+    UPDATE area_commitment_contract SET ctime = UNIXEPOCH() WHERE fbnr = NEW.fbnr;
+END;
+
+CREATE TRIGGER t_area_commitment_contract_u_ctime
+    BEFORE UPDATE ON area_commitment_contract FOR EACH ROW
+    WHEN (SELECT value FROM client_parameter WHERE param = 'ENABLE_TIME_TRIGGERS') = 1 AND OLD.ctime != NEW.ctime
+BEGIN
+    SELECT RAISE(ABORT, 'It is not allowed to change ctime');
+END;
+
+CREATE TRIGGER t_area_commitment_contract_i_mtime
+    AFTER INSERT ON area_commitment_contract FOR EACH ROW
+    WHEN (SELECT value FROM client_parameter WHERE param = 'ENABLE_TIME_TRIGGERS') = 1 AND NEW.mtime != UNIXEPOCH()
+BEGIN
+    UPDATE area_commitment_contract SET mtime = UNIXEPOCH() WHERE fbnr = NEW.fbnr;
+END;
+
+CREATE TRIGGER t_area_commitment_contract_u_mtime
+    AFTER UPDATE ON area_commitment_contract FOR EACH ROW
+    WHEN (SELECT value FROM client_parameter WHERE param = 'ENABLE_TIME_TRIGGERS') = 1 AND NEW.mtime != UNIXEPOCH()
+BEGIN
+    UPDATE area_commitment_contract SET mtime = UNIXEPOCH() WHERE fbnr = NEW.fbnr;
+END;
+
+CREATE TRIGGER t_area_commitment_i_ctime
+    AFTER INSERT ON area_commitment FOR EACH ROW
+    WHEN (SELECT value FROM client_parameter WHERE param = 'ENABLE_TIME_TRIGGERS') = 1 AND NEW.ctime != UNIXEPOCH()
+BEGIN
+    UPDATE area_commitment SET ctime = UNIXEPOCH() WHERE (fbnr, revnr) = (NEW.fbnr, NEW.revnr);
+END;
+
+CREATE TRIGGER t_area_commitment_u_ctime
+    BEFORE UPDATE ON area_commitment FOR EACH ROW
+    WHEN (SELECT value FROM client_parameter WHERE param = 'ENABLE_TIME_TRIGGERS') = 1 AND OLD.ctime != NEW.ctime
+BEGIN
+    SELECT RAISE(ABORT, 'It is not allowed to change ctime');
+END;
+
+CREATE TRIGGER t_area_commitment_i_mtime
+    AFTER INSERT ON area_commitment FOR EACH ROW
+    WHEN (SELECT value FROM client_parameter WHERE param = 'ENABLE_TIME_TRIGGERS') = 1 AND NEW.mtime != UNIXEPOCH()
+BEGIN
+    UPDATE area_commitment SET mtime = UNIXEPOCH() WHERE (fbnr, revnr) = (NEW.fbnr, NEW.revnr);
+END;
+
+CREATE TRIGGER t_area_commitment_u_mtime
+    AFTER UPDATE ON area_commitment FOR EACH ROW
+    WHEN (SELECT value FROM client_parameter WHERE param = 'ENABLE_TIME_TRIGGERS') = 1 AND NEW.mtime != UNIXEPOCH()
+BEGIN
+    UPDATE area_commitment SET mtime = UNIXEPOCH() WHERE (fbnr, revnr) = (NEW.fbnr, NEW.revnr);
+END;
+
+CREATE TRIGGER t_area_commitment_i_mtime_contract
+    AFTER INSERT ON area_commitment FOR EACH ROW
+    WHEN (SELECT value FROM client_parameter WHERE param = 'ENABLE_TIME_TRIGGERS') = 1
+BEGIN
+    UPDATE area_commitment_contract SET mtime = UNIXEPOCH() WHERE fbnr = NEW.fbnr;
+END;
+
+CREATE TRIGGER t_area_commitment_u_mtime_contract
+    AFTER UPDATE ON area_commitment FOR EACH ROW
+    WHEN (SELECT value FROM client_parameter WHERE param = 'ENABLE_TIME_TRIGGERS') = 1
+BEGIN
+    UPDATE area_commitment_contract SET mtime = UNIXEPOCH() WHERE fbnr = NEW.fbnr OR fbnr = OLD.fbnr;
+END;
+
+CREATE TRIGGER t_area_commitment_d_mtime_contract
+    AFTER DELETE ON area_commitment FOR EACH ROW
+    WHEN (SELECT value FROM client_parameter WHERE param = 'ENABLE_TIME_TRIGGERS') = 1
+BEGIN
+    UPDATE area_commitment_contract SET mtime = UNIXEPOCH() WHERE fbnr = OLD.fbnr;
+END;
+
+-- fix user fiddling - set actual year_from
+UPDATE area_commitment AS b
+SET fbnr = a.fbnr, revnr = b.fbnr, year_from = a.year_to + 1
+FROM area_commitment AS a
+WHERE a.fbnr < b.fbnr
+  AND COALESCE(a.year_from <= a.year_to, TRUE)
+  AND COALESCE(b.year_from <= b.year_to, TRUE)
+  AND SUBSTR(a.vtrgid, 0, 2) = SUBSTR(b.vtrgid, 0, 2)
+  AND (SELECT c.kgnr = d.kgnr AND COALESCE(c.rdnr = d.rdnr, TRUE) FROM area_commitment_contract c, area_commitment_contract d WHERE c.fbnr = a.fbnr AND d.fbnr = b.fbnr)
+  AND ((IIF(INSTR(a.gstnr, b.gstnr) > 0, 1, 0) + IIF(INSTR(b.gstnr, a.gstnr) > 0, 1, 0) + IIF(a.area = b.area, 2, 0) + (a.mgnr = b.mgnr)) > 1)
+  AND ((a.year_from = b.year_from AND b.year_to IS NULL AND a.year_to IS NOT NULL));
+
+-- simple
+UPDATE area_commitment AS b
+SET fbnr = a.fbnr, revnr = b.fbnr
+FROM area_commitment AS a
+WHERE a.fbnr < b.fbnr
+  AND COALESCE(a.year_from <= a.year_to, TRUE)
+  AND COALESCE(b.year_from <= b.year_to, TRUE)
+  AND SUBSTR(a.vtrgid, 0, 2) = SUBSTR(b.vtrgid, 0, 2)
+  AND (SELECT c.kgnr = d.kgnr AND COALESCE(c.rdnr = d.rdnr, TRUE) FROM area_commitment_contract c, area_commitment_contract d WHERE c.fbnr = a.fbnr AND d.fbnr = b.fbnr)
+  AND (a.gstnr = b.gstnr OR a.gstnr IN ('offen', '', '-')) AND a.area = b.area
+  AND a.year_to + 1 = b.year_from;
+
+-- copy comments
+UPDATE area_commitment_contract AS b
+SET comment = IIF(b.comment IS NULL, a.comment, CONCAT(b.comment, '; ', a.comment))
+FROM area_commitment_contract AS a
+WHERE a.comment IS NOT NULL AND a.fbnr IN (SELECT revnr FROM area_commitment WHERE revnr > 1 AND fbnr = b.fbnr);
+
+-- fix revnr
+UPDATE area_commitment AS b
+SET revnr = a.revnr + 1
+FROM area_commitment AS a
+WHERE a.fbnr = b.fbnr AND a.revnr < b.revnr;
+UPDATE area_commitment AS b
+SET revnr = a.revnr + 1
+FROM area_commitment AS a
+WHERE a.fbnr = b.fbnr AND a.revnr < b.revnr;
+UPDATE area_commitment AS b
+SET revnr = a.revnr + 1
+FROM area_commitment AS a
+WHERE a.fbnr = b.fbnr AND a.revnr < b.revnr;
+
+-- fix year_from
+UPDATE area_commitment AS b
+SET year_from = a.year_to + 1
+FROM area_commitment AS a
+WHERE a.fbnr = b.fbnr AND a.revnr = b.revnr - 1
+  AND a.year_to = b.year_from;
+UPDATE area_commitment AS b
+SET year_from = a.year_to + 1
+FROM area_commitment AS a
+WHERE a.fbnr = b.fbnr AND a.revnr = b.revnr - 1
+  AND a.year_to = b.year_from;
+
+-- delete unreferenced contracts
+DELETE FROM area_commitment_contract
+WHERE fbnr IN (SELECT c.fbnr FROM area_commitment_contract c
+                           LEFT JOIN area_commitment a ON a.fbnr = c.fbnr
+               WHERE a.fbnr IS NULL);
+
+UPDATE client_parameter SET value = '1' WHERE param = 'ENABLE_TIME_TRIGGERS';
diff --git a/Elwig/Services/AreaComService.cs b/Elwig/Services/AreaComService.cs
index 1e32b44..29df618 100644
--- a/Elwig/Services/AreaComService.cs
+++ b/Elwig/Services/AreaComService.cs
@@ -22,33 +22,36 @@ namespace Elwig.Services {
         public static void ClearInputs(this AreaComAdminViewModel vm) {
         }
 
+        public static void FillInputs(this AreaComAdminViewModel vm, AreaComContract c) {
+            vm.FbNr = c.FbNr;
+            vm.Period = c.YearTo == null ? $"ab {c.YearFrom}" : $"{c.YearFrom}\u2013{c.YearTo}";
+            vm.Comment = c.Comment;
+            vm.Kg = ControlUtils.GetItemFromSourceWithPk(vm.KgSource, c.KgNr) as AT_Kg;
+            vm.Rd = ControlUtils.GetItemFromSourceWithPk(vm.RdSource, c.KgNr, c.RdNr) as WbRd;
+        }
+
         public static void FillInputs(this AreaComAdminViewModel vm, AreaCom a) {
-            vm.FbNr = a.FbNr;
             vm.MgNr = a.MgNr;
             vm.YearFrom = a.YearFrom;
             vm.YearTo = a.YearTo;
             vm.AreaComType = ControlUtils.GetItemFromSourceWithPk(vm.AreaComTypeSource, a.VtrgId) as AreaComType;
             vm.WineCult = ControlUtils.GetItemFromSourceWithPk(vm.WineCultSource, a.CultId) as WineCult;
-            vm.Comment = a.Comment;
-            vm.Kg = ControlUtils.GetItemFromSourceWithPk(vm.KgSource, a.KgNr) as AT_Kg;
-            vm.Rd = ControlUtils.GetItemFromSourceWithPk(vm.RdSource, a.KgNr, a.RdNr) as WbRd;
             vm.GstNr = a.GstNr;
             vm.Area = a.Area;
         }
 
-        public static async Task<(List<string>, IQueryable<AreaCom>, List<string>)> GetFilters(this AreaComAdminViewModel vm, AppDbContext ctx) {
+        public static async Task<(List<string>, IQueryable<AreaComContract>, IQueryable<AreaCom>, List<string>)> GetFilters(this AreaComAdminViewModel vm, AppDbContext ctx) {
             List<string> filterNames = [];
             IQueryable<AreaCom> areaComQuery = ctx.AreaCommitments.Where(a => a.MgNr == vm.FilterMember.MgNr).OrderBy(a => a.FbNr);
-            if (vm.ShowOnlyActiveAreaComs) {
-                areaComQuery = Utils.ActiveAreaCommitments(areaComQuery, Utils.CurrentLastSeason);
-                filterNames.Add($"laufend {Utils.CurrentLastSeason}");
+            if (vm.FilterSeason is int season) {
+                areaComQuery = Utils.ActiveAreaCommitments(areaComQuery, season);
+                filterNames.Add($"laufend {season}");
             }
 
             var filterVar = new List<string>();
             var filterNotVar = new List<string>();
             var filterAttr = new List<string>();
             var filterNotAttr = new List<string>();
-            var filterSeasons = new List<int>();
 
             var filter = vm.TextFilter;
             if (filter.Count > 0) {
@@ -88,10 +91,6 @@ namespace Elwig.Services {
                         filter.RemoveAt(i--);
                         filterNames.Add($"ohne {var[e[1..3].ToUpper()].Name}");
                         filterNames.Add($"ohne Attribut {attrId[e[3..].ToUpper()].Name}");
-                    } else if (e.Length == 4 && int.TryParse(e, out var year)) {
-                        filterSeasons.Add(year);
-                        filter.RemoveAt(i--);
-                        filterNames.Add($"laufend {e}");
                     }
                 }
 
@@ -99,38 +98,50 @@ namespace Elwig.Services {
                 if (filterNotVar.Count > 0) areaComQuery = areaComQuery.Where(a => !filterNotVar.Contains(a.AreaComType.WineVar.SortId));
                 if (filterAttr.Count > 0) areaComQuery = areaComQuery.Where(a => a.AreaComType.WineAttr!.AttrId != null && filterAttr.Contains(a.AreaComType.WineAttr.AttrId));
                 if (filterNotAttr.Count > 0) areaComQuery = areaComQuery.Where(a => a.AreaComType.WineAttr!.AttrId == null || !filterNotAttr.Contains(a.AreaComType.WineAttr.AttrId));
-                foreach (var year in filterSeasons) areaComQuery = Utils.ActiveAreaCommitments(areaComQuery, year);
             }
 
-            return (filterNames, areaComQuery, filter);
+            IQueryable<AreaComContract> contracts = areaComQuery
+                .Select(c => c.Contract).Distinct()
+                .OrderBy(c => c.FbNr);
+
+            return (filterNames, contracts, areaComQuery, filter);
         }
 
-        public static async Task<int> UpdateAreaCommitment(this AreaComAdminViewModel vm, int? oldFbNr) {
+        public static async Task<(int FbNr, int RevNr)> UpdateAreaCommitment(this AreaComAdminViewModel vm, int? oldFbNr, int? revNr) {
             int newFbNr = vm.FbNr!.Value;
 
             return await Task.Run(async () => {
                 using var ctx = new AppDbContext();
+                var c = new AreaComContract {
+                    FbNr = oldFbNr ?? newFbNr,
+                    Comment = string.IsNullOrEmpty(vm.Comment) ? null : vm.Comment,
+                    KgNr = vm.Kg!.KgNr,
+                    RdNr = vm.Rd?.RdNr,
+                };
                 var a = new AreaCom {
                     FbNr = oldFbNr ?? newFbNr,
+                    RevNr = revNr ?? await ctx.NextRevNr(oldFbNr ?? newFbNr),
                     MgNr = vm.MgNr!.Value,
                     YearFrom = vm.YearFrom,
                     YearTo = vm.YearTo,
                     VtrgId = vm.AreaComType!.VtrgId,
                     CultId = vm.WineCult?.CultId,
-                    Comment = string.IsNullOrEmpty(vm.Comment) ? null : vm.Comment,
-                    KgNr = vm.Kg!.KgNr,
-                    RdNr = vm.Rd?.RdNr,
                     GstNr = vm.GstNr?.Trim() ?? "-",
                     Area = vm.Area!.Value,
                 };
 
                 if (vm.Rd?.RdNr == 0) {
-                    vm.Rd.RdNr = await ctx.NextRdNr(a.KgNr);
-                    a.RdNr = vm.Rd.RdNr;
+                    vm.Rd.RdNr = await ctx.NextRdNr(c.KgNr);
+                    c.RdNr = vm.Rd.RdNr;
                     ctx.Add(vm.Rd);
                 }
 
                 if (oldFbNr != null) {
+                    ctx.Update(c);
+                } else {
+                    ctx.Add(c);
+                }
+                if (revNr != null) {
                     ctx.Update(a);
                 } else {
                     ctx.Add(a);
@@ -139,10 +150,10 @@ namespace Elwig.Services {
                 await ctx.SaveChangesAsync();
 
                 if (newFbNr != a.FbNr) {
-                    await ctx.Database.ExecuteSqlAsync($"UPDATE area_commitment SET fbnr = {newFbNr} WHERE fbnr = {oldFbNr}");
+                    await ctx.Database.ExecuteSqlAsync($"UPDATE area_commitment_contract SET fbnr = {newFbNr} WHERE fbnr = {oldFbNr}");
                 }
 
-                return newFbNr;
+                return (newFbNr, a.RevNr);
             });
         }
 
@@ -256,7 +267,16 @@ namespace Elwig.Services {
         public static async Task DeleteAreaCom(int fbnr) {
             await Task.Run(async () => {
                 using var ctx = new AppDbContext();
-                var l = (await ctx.AreaCommitments.FindAsync(fbnr))!;
+                var l = (await ctx.AreaCommitmentContracts.FindAsync(fbnr))!;
+                ctx.Remove(l);
+                await ctx.SaveChangesAsync();
+            });
+        }
+
+        public static async Task DeleteAreaComRevision(int fbnr, int revnr) {
+            await Task.Run(async () => {
+                using var ctx = new AppDbContext();
+                var l = (await ctx.AreaCommitments.FindAsync(fbnr, revnr))!;
                 ctx.Remove(l);
                 await ctx.SaveChangesAsync();
             });
diff --git a/Elwig/Services/MemberService.cs b/Elwig/Services/MemberService.cs
index 5dc9009..849c7cf 100644
--- a/Elwig/Services/MemberService.cs
+++ b/Elwig/Services/MemberService.cs
@@ -556,8 +556,10 @@ namespace Elwig.Services {
                                 .ToListAsync();
                             var areaComs = await query
                                 .SelectMany(m => m.AreaCommitments)
+                                .Select(c => c.Contract).Distinct()
                                 .Include(c => c.Rd)
                                 .Include(c => c.Kg.Gl)
+                                .Include(c => c.Revisions)
                                 .ToListAsync();
                             var wbKgs = members
                                 .Where(m => m.DefaultWbKg != null)
@@ -681,19 +683,17 @@ namespace Elwig.Services {
                         .Where(c => c.MgNr == predecessor && (c.YearTo == null || c.YearTo >= year))
                         .ToListAsync();
 
-                    var fbNr = await ctx.NextFbNr();
-                    ctx.AddRange(areaComs.Select((c, i) => new AreaCom {
-                        FbNr = fbNr + i,
+                    ctx.AddRange(await Task.WhenAll(areaComs.Select(async (c, i) => new AreaCom {
+                        FbNr = c.FbNr,
+                        RevNr = await ctx.NextRevNr(c.FbNr),
                         MgNr = m.MgNr,
                         VtrgId = c.VtrgId,
                         CultId = c.CultId,
                         Area = c.Area,
-                        KgNr = c.KgNr,
                         GstNr = c.GstNr,
-                        RdNr = c.RdNr,
-                        YearFrom = vm.MaintainAreaComYearFrom ? c.YearFrom : year,
+                        YearFrom = year,
                         YearTo = c.YearTo,
-                    }));
+                    })));
 
                     foreach (var ac in areaComs)
                         ac.YearTo = year - 1;
diff --git a/Elwig/Services/SyncService.cs b/Elwig/Services/SyncService.cs
index 2b0cfa6..c06c9cf 100644
--- a/Elwig/Services/SyncService.cs
+++ b/Elwig/Services/SyncService.cs
@@ -16,6 +16,7 @@ namespace Elwig.Services {
     public static class SyncService {
 
         public static readonly Expression<Func<Member, bool>> ChangedMembers = (m) => ((m.XTime == null && m.MTime > 1751328000) || m.MTime > m.XTime) && (m.ITime == null || m.MTime > m.ITime);
+        public static readonly Expression<Func<AreaComContract, bool>> ChangedAreaComContracts = (c) => ((c.XTime == null && c.MTime > 1751328000) || c.MTime > c.XTime) && (c.ITime == null || c.MTime > c.ITime);
         public static readonly Expression<Func<Delivery, bool>> ChangedDeliveries = (d) => ((d.XTime == null && d.MTime > 1751328000) || d.MTime > d.XTime) && (d.ITime == null || d.MTime > d.ITime);
 
         public static async Task Upload(string url, string username, string password, IQueryable<Member> query, IEnumerable<string> filterNames) {
@@ -32,9 +33,11 @@ namespace Elwig.Services {
                     .ToListAsync();
                 var areaComs = await query
                     .SelectMany(m => m.AreaCommitments)
-                    .OrderBy(c => c.MgNr).ThenBy(c => c.FbNr)
+                    .Select(c => c.Contract).Distinct()
+                    .OrderBy(c => c.FbNr)
                     .Include(c => c.Rd)
                     .Include(c => c.Kg.Gl)
+                    .Include(c => c.Revisions)
                     .ToListAsync();
                 var wbKgs = members
                     .Where(m => m.DefaultWbKg != null)
@@ -50,7 +53,7 @@ namespace Elwig.Services {
                     var exportedAt = DateTime.Now;
                     await ElwigData.Export(path, members, areaComs, wbKgs, filterNames);
                     await Utils.UploadExportData(path, url, username, password);
-                    await UpdateExportedAt(members, [], exportedAt);
+                    await UpdateExportedAt(members, areaComs, [], exportedAt);
                     MessageBox.Show($"Hochladen von {members.Count:N0} Mitgliedern erfolgreich!", "Mitglieder hochgeladen",
                         MessageBoxButton.OK, MessageBoxImage.Information);
                 }
@@ -89,7 +92,7 @@ namespace Elwig.Services {
                     var exportedAt = DateTime.Now;
                     await ElwigData.Export(path, list, wbKgs, filterNames);
                     await Utils.UploadExportData(path, url, username, password);
-                    await UpdateExportedAt([], list, exportedAt);
+                    await UpdateExportedAt([], [], list, exportedAt);
                     MessageBox.Show($"Hochladen von {list.Count:N0} Lieferungen erfolgreich!", "Lieferungen hochgeladen",
                         MessageBoxButton.OK, MessageBoxImage.Information);
                 }
@@ -106,7 +109,7 @@ namespace Elwig.Services {
             try {
                 var path = Path.Combine(App.TempPath, $"{DateTime.Now:yyyy-MM-dd_HH-mm-ss}_{App.ZwstId}.elwig.zip");
                 List<Member> members;
-                List<AreaCom> areaComs;
+                List<AreaComContract> areaComs;
                 List<Delivery> deliveries;
                 using (var ctx = new AppDbContext()) {
                     members = await ctx.Members
@@ -118,12 +121,12 @@ namespace Elwig.Services {
                         .OrderBy(m => m.MgNr)
                         .AsSplitQuery()
                         .ToListAsync();
-                    areaComs = await ctx.Members
-                       .Where(ChangedMembers)
-                       .SelectMany(m => m.AreaCommitments)
+                    areaComs = await ctx.AreaCommitmentContracts
+                       .Where(ChangedAreaComContracts)
                        .Include(c => c.Rd)
                        .Include(c => c.Kg.Gl)
-                       .OrderBy(c => c.MgNr).ThenBy(c => c.FbNr)
+                       .Include(c => c.Revisions)
+                       .OrderBy(c => c.FbNr)
                        .ToListAsync();
                     deliveries = await ctx.Deliveries
                         .Where(ChangedDeliveries)
@@ -151,13 +154,13 @@ namespace Elwig.Services {
                     var exportedAt = DateTime.Now;
                     await (new ElwigData.ElwigExport {
                         Members = (members, ["geändert seit letztem Export"]),
-                        AreaComs = (areaComs, ["von exportierten Mitgliedern"]),
+                        AreaComs = (areaComs, ["geändert seit letztem Export"]),
                         Deliveries = (deliveries, ["geändert seit letzem Export"]),
                         WbKgs = (wbKgs, ["von exportierten Mitgliedern, Flächenbindungen und Lieferungen"]),
                     }).Export(path);
                     await Utils.UploadExportData(path, url, username, password);
-                    await UpdateExportedAt(members, deliveries, exportedAt);
-                    MessageBox.Show($"Hochladen von {members.Count:N0} Mitgliedern und {deliveries.Count:N0} Lieferungen erfolgreich!", "Mitglieder und Lieferungen hochladen",
+                    await UpdateExportedAt(members, areaComs, deliveries, exportedAt);
+                    MessageBox.Show($"Hochladen von {members.Count:N0} Mitgliedern, {areaComs.Count:N0} Flächenbindungsverträgen, und {deliveries.Count:N0} Lieferungen erfolgreich!", "Mitglieder und Lieferungen hochladen",
                         MessageBoxButton.OK, MessageBoxImage.Information);
                 }
             } catch (HttpRequestException exc) {
@@ -195,7 +198,7 @@ namespace Elwig.Services {
                     var exportedAt = DateTime.Now;
                     await ElwigData.Export(path, deliveries, wbKgs, [$"{year}", $"Zweigstelle {App.BranchName}"]);
                     await Utils.UploadExportData(path, url, username, password);
-                    await UpdateExportedAt([], deliveries, exportedAt);
+                    await UpdateExportedAt([], [], deliveries, exportedAt);
                     MessageBox.Show($"Hochladen von {deliveries.Count:N0} Lieferungen erfolgreich!", "Lieferungen hochladen",
                         MessageBoxButton.OK, MessageBoxImage.Information);
                 }
@@ -251,19 +254,21 @@ namespace Elwig.Services {
             }
         }
 
-        private static async Task UpdateExportedAt(IEnumerable<Member> member, IEnumerable<Delivery> deliveries, DateTime dateTime) {
+        private static async Task UpdateExportedAt(IEnumerable<Member> member, IEnumerable<AreaComContract> contracts, IEnumerable<Delivery> deliveries, DateTime dateTime) {
             var timestamp = ((DateTimeOffset)dateTime.ToUniversalTime()).ToUnixTimeSeconds();
             var mgnrs = string.Join(",", member.Select(m => $"{m.MgNr}").Append("0"));
+            var fbnrs = string.Join(",", contracts.Select(c => $"{c.FbNr}").Append("0"));
             var dids = string.Join(",", deliveries.Select(d => $"({d.Year},{d.DId})").Append("(0,0)"));
             using (var cnx = await AppDbContext.ConnectAsync()) {
                 await cnx.ExecuteBatch($"""
                     BEGIN;
-                    UPDATE client_parameter SET value = '0' WHERE param = 'ENABLE_TIME_TRIGGERS';
-                    UPDATE member           SET xtime = {timestamp} WHERE mgnr IN ({mgnrs});
-                    UPDATE area_commitment  SET xtime = {timestamp} WHERE mgnr IN ({mgnrs});
-                    UPDATE delivery         SET xtime = {timestamp} WHERE (year, did) IN ({dids});
-                    UPDATE delivery_part    SET xtime = {timestamp} WHERE (year, did) IN ({dids});
-                    UPDATE client_parameter SET value = '1' WHERE param = 'ENABLE_TIME_TRIGGERS';
+                    UPDATE client_parameter          SET value = '0' WHERE param = 'ENABLE_TIME_TRIGGERS';
+                    UPDATE member                    SET xtime = {timestamp} WHERE mgnr IN ({mgnrs});
+                    UPDATE area_commitment_contract  SET xtime = {timestamp} WHERE fbnr IN ({fbnrs});
+                    UPDATE area_commitment           SET xtime = {timestamp} WHERE fbnr IN ({fbnrs});
+                    UPDATE delivery                  SET xtime = {timestamp} WHERE (year, did) IN ({dids});
+                    UPDATE delivery_part             SET xtime = {timestamp} WHERE (year, did) IN ({dids});
+                    UPDATE client_parameter          SET value = '1' WHERE param = 'ENABLE_TIME_TRIGGERS';
                     COMMIT;
                     """);
             }
@@ -272,7 +277,7 @@ namespace Elwig.Services {
 
         public static async Task<bool> ChangesAvailable(AppDbContext ctx, string url, string username, string password) {
             try {
-                return await ctx.Members.AnyAsync(ChangedMembers) || await ctx.Deliveries.AnyAsync(ChangedDeliveries) || (Utils.HasInternetConnectivity() && (await GetFilesToImport(url, username, password)).Count > 0);
+                return await ctx.Members.AnyAsync(ChangedMembers) || await ctx.AreaCommitmentContracts.AnyAsync(ChangedAreaComContracts) || await ctx.Deliveries.AnyAsync(ChangedDeliveries) || (Utils.HasInternetConnectivity() && (await GetFilesToImport(url, username, password)).Count > 0);
             } catch {
                 return false;
             }
diff --git a/Elwig/ViewModels/AreaComAdminViewModel.cs b/Elwig/ViewModels/AreaComAdminViewModel.cs
index c1fec97..151486a 100644
--- a/Elwig/ViewModels/AreaComAdminViewModel.cs
+++ b/Elwig/ViewModels/AreaComAdminViewModel.cs
@@ -20,7 +20,11 @@ namespace Elwig.ViewModels {
         }
 
         [ObservableProperty]
-        private bool _showOnlyActiveAreaComs;
+        private string? _filterSeasonString;
+        public int? FilterSeason {
+            get => int.TryParse(FilterSeasonString, out var year) ? year : null;
+            set => FilterSeasonString = $"{value}";
+        }
 
         [ObservableProperty]
         private string? _fbNrString;
@@ -46,6 +50,8 @@ namespace Elwig.ViewModels {
             get => int.TryParse(YearToString, out var year) ? year : null;
             set => YearToString = $"{value}";
         }
+        [ObservableProperty]
+        private string? _period;
 
         [ObservableProperty]
         private AreaComType? _areaComType;
diff --git a/Elwig/ViewModels/MemberAdminViewModel.cs b/Elwig/ViewModels/MemberAdminViewModel.cs
index d10871c..8064cd0 100644
--- a/Elwig/ViewModels/MemberAdminViewModel.cs
+++ b/Elwig/ViewModels/MemberAdminViewModel.cs
@@ -11,7 +11,6 @@ namespace Elwig.ViewModels {
     public partial class MemberAdminViewModel : ObservableObject {
 
         public int? TransferPredecessorAreaComs = null;
-        public bool MaintainAreaComYearFrom = false;
         public int? CancelAreaComs = null;
 
         public ObservableCollection<KeyValuePair<string, string>> PhoneNrTypes { get; set; } = new(Utils.PhoneNrTypes);
diff --git a/Elwig/Windows/AreaComAdminWindow.xaml b/Elwig/Windows/AreaComAdminWindow.xaml
index 9970170..a2e74c1 100644
--- a/Elwig/Windows/AreaComAdminWindow.xaml
+++ b/Elwig/Windows/AreaComAdminWindow.xaml
@@ -7,7 +7,7 @@
         xmlns:local="clr-namespace:Elwig.Windows"
         xmlns:ctrl="clr-namespace:Elwig.Controls"
         xmlns:vm="clr-namespace:Elwig.ViewModels"
-        Title="{Binding Title}" Height="600" MinHeight="450" Width="1000" MinWidth="860"
+        Title="{Binding Title}" Height="600" MinHeight="550" Width="1000" MinWidth="860"
         Loaded="Window_Loaded">
     <Window.DataContext>
         <vm:AreaComAdminViewModel/>
@@ -57,7 +57,7 @@
             <RowDefinition Height="24"/>
         </Grid.RowDefinitions>
         <Grid.ColumnDefinitions>
-            <ColumnDefinition Width="3*" MinWidth="500"/>
+            <ColumnDefinition Width="2*" MinWidth="500"/>
             <ColumnDefinition Width="5"/>
             <ColumnDefinition Width="*" MinWidth="280"/>
         </Grid.ColumnDefinitions>
@@ -78,7 +78,7 @@
             </Grid.ColumnDefinitions>
 
             <TextBox x:Name="SearchInput" Text="{Binding SearchQuery, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
-                     Grid.ColumnSpan="3" Margin="5,5,190,0" IsReadOnly="False"
+                     Grid.ColumnSpan="3" Margin="5,5,66,0" IsReadOnly="False"
                      TextChanged="SearchInput_TextChanged">
                 <TextBox.ToolTip>
                     <TextBlock>
@@ -94,9 +94,10 @@
                     </TextBlock>
                 </TextBox.ToolTip>
             </TextBox>
-            <CheckBox x:Name="ActiveAreaCommitmentInput" Content="Nur laufende anzeigen (2020)" IsChecked="{Binding ShowOnlyActiveAreaComs}"
-                      Checked="ActiveAreaCommitmentInput_Changed" Unchecked="ActiveAreaCommitmentInput_Changed"
-                      HorizontalAlignment="Right" Margin="0,10,10,0" VerticalAlignment="Top" Grid.Column="1" Grid.ColumnSpan="2"/>
+            <ctrl:IntegerUpDown x:Name="SeasonInput" Text="{Binding FilterSeasonString, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
+                                Grid.ColumnSpan="3" Height="25" Width="56" FontSize="14" Minimum="1900" Maximum="9999"
+                                Margin="0,5,5,0" VerticalAlignment="Top" HorizontalAlignment="Right"
+                                TextChanged="SeasonInput_TextChanged"/>
 
             <DataGrid x:Name="AreaCommitmentList" AutoGenerateColumns="False" HeadersVisibility="Column" IsReadOnly="True" GridLinesVisibility="None" SelectionMode="Single"
                       CanUserDeleteRows="False" CanUserResizeRows="False" CanUserAddRows="False" SelectionChanged="AreaCommitmentList_SelectionChanged" Grid.Column="0" Grid.Row="1"
@@ -110,25 +111,24 @@
                         </DataGridTextColumn.CellStyle>
                     </DataGridTextColumn>
                     <DataGridTextColumn Header="Katastralgemeinde" Binding="{Binding Kg.AtKg.Name}" Width="130"/>
-                    <DataGridTextColumn Header="Sorte" Binding="{Binding AreaComType.WineVar.SortId}" Width="50">
+                    <DataGridTextColumn Header="Sorte" Binding="{Binding Latest.AreaComType.VtrgId}" Width="50">
                         <DataGridTextColumn.CellStyle>
                             <Style>
-                                <Setter Property="TextBlock.Foreground" Value="{Binding AreaComType.WineVar.Color}"/>
+                                <Setter Property="TextBlock.Foreground" Value="{Binding Latest.AreaComType.WineVar.Color}"/>
                                 <Setter Property="TextBlock.TextAlignment" Value="Center"/>
                             </Style>
                         </DataGridTextColumn.CellStyle>
                     </DataGridTextColumn>
-                    <DataGridTextColumn Header="Fläche" Binding="{Binding Area, StringFormat='{}{0:N0} m² '}" Width="80">
+                    <DataGridTextColumn Header="Fläche" Binding="{Binding Latest.Area, StringFormat='{}{0:N0} m² '}" Width="80">
                         <DataGridTextColumn.CellStyle>
                             <Style>
                                 <Setter Property="TextBlock.TextAlignment" Value="Right"/>
                             </Style>
                         </DataGridTextColumn.CellStyle>
                     </DataGridTextColumn>
-                    <DataGridTextColumn Header="Attribut"           Binding="{Binding AreaComType.WineAttr.Name}" Width="100"/>
                     <DataGridTextColumn Header="Ried"               Binding="{Binding Rd.Name}"       Width="130"/>
-                    <DataGridTextColumn Header="Parzelle"           Binding="{Binding GstNr}"         Width="130"/>
-                    <DataGridTextColumn Header="Bewirt."            Binding="{Binding WineCult.Name}" Width="60"/>
+                    <DataGridTextColumn Header="Parzelle"           Binding="{Binding Latest.GstNr}"         Width="130"/>
+                    <DataGridTextColumn Header="Bewirt."            Binding="{Binding Latest.WineCult.Name}" Width="60"/>
                     <DataGridTextColumn Header="Von"                Binding="{Binding YearFrom}"      Width="48"/>
                     <DataGridTextColumn Header="Bis"                Binding="{Binding YearTo}"        Width="48"/>
                 </DataGrid.Columns>
@@ -177,91 +177,119 @@
 
         <Grid Grid.Column="2" Grid.Row="1">
             <Grid.RowDefinitions>
-                <RowDefinition Height="1.125*"/>
-                <RowDefinition Height="1*"/>
+                <RowDefinition Height="*"/>
+                <RowDefinition Height="230"/>
             </Grid.RowDefinitions>
 
-            <GroupBox Header="Vertrag" Grid.Column="2" Grid.Row="0" Grid.RowSpan="1" Margin="5,5,5,5">
+            <GroupBox Header="Vertrag" Grid.Row="0" Margin="5,5,5,5">
                 <Grid>
                     <Grid.ColumnDefinitions>
                         <ColumnDefinition Width="80"/>
-                        <ColumnDefinition Width="48"/>
+                        <ColumnDefinition Width="60"/>
                         <ColumnDefinition Width="60"/>
                         <ColumnDefinition Width="*"/>
                     </Grid.ColumnDefinitions>
 
-                    <Label Content="MgNr.:" Margin="10,10,0,0" Grid.Column="0"/>
-                    <TextBox x:Name="MgNrInput" Text="{Binding MgNrString, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" IsEnabled="False"
-                             Margin="0,10,0,0" Width="48" HorizontalAlignment="Left" Grid.Column="1" TextAlignment="Right"/>
-
-                    <Label Content="FbNr.:" Margin="10,10,0,0" Grid.Column="2"/>
+                    <Label Content="FB-Nr.:" Margin="10,10,0,0" Grid.Column="0"/>
                     <TextBox x:Name="FbNrInput" Text="{Binding FbNrString, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
-                             Margin="0,10,10,0" Width="56" HorizontalAlignment="Left" Grid.Column="3" TextAlignment="Right"
+                             Margin="0,10,0,0" Width="56" HorizontalAlignment="Left" Grid.Column="1" TextAlignment="Right"
                              TextChanged="FbNrInput_TextChanged" LostFocus="FbNrInput_LostFocus"/>
 
-                    <Label Content="Zeitraum:" Margin="10,40,0,0" Grid.Column="0"/>
-                    <TextBox x:Name="YearFromInput" Text="{Binding YearFromString, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
-                             Margin="0,40,10,0" Width="40" HorizontalAlignment="Left" Grid.Column="1" Grid.ColumnSpan="2" TextAlignment="Right"
-                             TextChanged="IntegerInput_TextChanged"/>
-                    <Label Content="–" Grid.Column="1" Grid.ColumnSpan="3" Margin="45,40,0,0"/>
-                    <TextBox x:Name="YearToInput" Text="{Binding YearToString, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
-                             Margin="60,40,10,0" Width="40" HorizontalAlignment="Left" Grid.Column="1" Grid.ColumnSpan="3" TextAlignment="Right"
-                             TextChanged="IntegerInput_TextChanged"/>
+                    <Label Content="Laufzeit:" Margin="10,10,0,0" Grid.Column="2"/>
+                    <TextBlock x:Name="Period" Text="{Binding Period}"
+                               Margin="0,14,10,0" Grid.Column="3" TextWrapping="NoWrap" VerticalAlignment="Top"/>
 
-                    <Label Content="Vertragsart:" Margin="10,70,0,0" Grid.Column="0" Grid.ColumnSpan="2"/>
-                    <ComboBox x:Name="AreaComTypeInput" SelectedItem="{Binding AreaComType, Mode=TwoWay}" ItemsSource="{Binding AreaComTypeSource, Mode=TwoWay}"
-                              ItemTemplate="{StaticResource AreaCommitmentTypeTemplate}" TextSearch.TextPath="DisplayName"
-                              HorizontalAlignment="Stretch" Margin="0,70,40,10" Grid.Column="1" Grid.ColumnSpan="3"/>
-                    <Button x:Name="AreaComTypeDetailsButton" Content="&#xE712;" FontFamily="Segoe MDL2 Assets" FontSize="14" Padding="0,1,0,0"
-                            Click="AreaComTypeDetailsButton_Click"
+                    <Label Content="KG:" Margin="10,40,0,0" Grid.Column="0"/>
+                    <ComboBox x:Name="KgInput" SelectedItem="{Binding Kg, Mode=TwoWay}" ItemsSource="{Binding KgSource, Mode=TwoWay}"
+                              ItemTemplate="{StaticResource KgNrTemplate}" TextSearch.TextPath="Name"
+                              HorizontalAlignment="Stretch" Margin="0,40,40,10" Grid.Column="1" Grid.ColumnSpan="3"
+                              SelectionChanged="KgInput_SelectionChanged"/>
+                    <Button x:Name="KgDetailsButton" Content="&#xE712;" FontFamily="Segoe MDL2 Assets" FontSize="14" Padding="0,1,0,0"
+                            Click="KgDetailsButton_Click"
+                            Grid.Column="3" VerticalAlignment="Top" HorizontalAlignment="Right" Width="25" Height="25" Margin="10,40,10,10"/>
+
+                    <Label Content="Ried:" Margin="10,70,0,0" Grid.Column="0"/>
+                    <ComboBox x:Name="RdInput" SelectedItem="{Binding RdObj, Mode=TwoWay}" ItemsSource="{Binding RdSource, Mode=TwoWay}"
+                              DisplayMemberPath="Name" TextSearch.TextPath="Name" IsEditable="True"
+                              HorizontalAlignment="Stretch" Margin="0,70,40,10" Grid.Column="1" Grid.ColumnSpan="3"
+                              SelectionChanged="RdInput_SelectionChanged"/>
+                    <Button x:Name="RdAddButton" Content="&#xE73E;" FontFamily="Segoe MDL2 Assets" FontSize="16" Padding="0,0,0,0" IsEnabled="False"
+                            Click="RdAddButton_Click"
                             Grid.Column="3" VerticalAlignment="Top" HorizontalAlignment="Right" Width="25" Height="25" Margin="10,70,10,10"/>
 
-                    <Label Content="Bewirt.-Art:" Margin="10,100,0,0" Grid.Column="0" Grid.ColumnSpan="2"/>
-                    <ComboBox x:Name="WineCultivationInput" SelectedItem="{Binding WineCultObj, Mode=TwoWay}" ItemsSource="{Binding WineCultSource, Mode=TwoWay}"
-                              DisplayMemberPath="Name" TextSearch.TextPath="Name"
-                              HorizontalAlignment="Stretch" Margin="0,100,10,0" Grid.Column="1" Grid.ColumnSpan="3"/>
-
-                    <Label Content="Anmerkung:" Margin="10,130,0,0" Grid.Column="0" Grid.ColumnSpan="2"/>
+                    <Label Content="Anmerkung:" Margin="10,100,0,0" Grid.Column="0" Grid.ColumnSpan="2"/>
                     <TextBox x:Name="CommentInput" Text="{Binding Comment, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
                              TextChanged="TextBox_TextChanged"
-                             HorizontalAlignment="Stretch" Margin="0,130,10,0" Grid.Column="1" Grid.ColumnSpan="3"/>
+                             HorizontalAlignment="Stretch" Margin="0,100,10,0" Grid.Column="1" Grid.ColumnSpan="3"/>
+
+                    <ListBox x:Name="RevisionList" Grid.ColumnSpan="4" Margin="5,135,5,5"
+                             SelectionChanged="RevisionList_SelectionChanged">
+                        <ListBox.ItemTemplate>
+                            <DataTemplate>
+                                <StackPanel Orientation="Horizontal">
+                                    <TextBlock Text="{Binding YearFrom}" Width="28" TextAlignment="Right" Margin="0,0,0,0"/>
+                                    <TextBlock Text="&#x2013;" TextAlignment="Center" Margin="0,0,0,0"/>
+                                    <TextBlock Text="{Binding YearTo}" Width="28" TextAlignment="Left" Margin="0,0,0,0"/>
+                                    <TextBlock Text="{Binding VtrgId}" Width="40" TextAlignment="Center" Foreground="{Binding AreaComType.WineVar.Color}"/>
+                                    <TextBlock Text="{Binding Area, StringFormat='{}{0:N0} m²'}" Width="60" TextAlignment="Right" Padding="0,0,10,0"/>
+                                    <TextBlock Text="{Binding Member.AdministrativeName}"/>
+                                </StackPanel>
+                            </DataTemplate>
+                        </ListBox.ItemTemplate>
+                    </ListBox>
                 </Grid>
             </GroupBox>
 
-            <GroupBox Header="Lage" Grid.Column="2" Grid.Row="1" Grid.RowSpan="1" Margin="5,5,5,10">
+            <GroupBox Header="Revision" Grid.Row="1" Margin="5,5,5,10">
                 <Grid>
                     <Grid.ColumnDefinitions>
                         <ColumnDefinition Width="80"/>
                         <ColumnDefinition Width="*"/>
                     </Grid.ColumnDefinitions>
 
-                    <Label Content="KG:" Margin="10,10,0,0" Grid.Column="0"/>
-                    <ComboBox x:Name="KgInput" SelectedItem="{Binding Kg, Mode=TwoWay}" ItemsSource="{Binding KgSource, Mode=TwoWay}"
-                              ItemTemplate="{StaticResource KgNrTemplate}" TextSearch.TextPath="Name"
-                              HorizontalAlignment="Stretch" Margin="0,10,40,10" Grid.Column="1"
-                              SelectionChanged="KgInput_SelectionChanged"/>
-                    <Button x:Name="KgDetailsButton" Content="&#xE712;" FontFamily="Segoe MDL2 Assets" FontSize="14" Padding="0,1,0,0"
-                            Click="KgDetailsButton_Click"
-                            Grid.Column="1" VerticalAlignment="Top" HorizontalAlignment="Right" Width="25" Height="25" Margin="10,10,10,10"/>
+                    <Label Content="Mitglied:" Margin="10,10,0,0" Grid.Column="0"/>
+                    <TextBox x:Name="MgNrInput" Text="{Binding MgNrString, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
+                             Width="48" Grid.Row="1" Grid.Column="1" Margin="0,10,0,0" HorizontalAlignment="Left" TextAlignment="Right"
+                             TextChanged="MgNrInput_TextChanged" LostFocus="MgNrInput_LostFocus"/>
+                    <ComboBox x:Name="MemberInput"
+                              Grid.Column="1" Margin="53,10,40,10" IsEditable="True"
+                              ItemTemplate="{StaticResource MemberAdminNameTemplate}" TextSearch.TextPath="AdministrativeName"
+                              SelectionChanged="MemberInput_SelectionChanged"/>
+                    <Button x:Name="MemberReferenceButton" Grid.Column="1" Height="25" Width="25" FontFamily="Segoe MDL2 Assets" Content="&#xEE35;" Padding="0,0,0,0"
+                            Margin="10,10,10,10" VerticalAlignment="Top" HorizontalAlignment="Right" ToolTip="Zu Mitglied springen"
+                            Click="MemberReferenceButton_Click"/>
 
-                    <Label Content="Ried:" Margin="10,40,0,0" Grid.Column="0"/>
-                    <ComboBox x:Name="RdInput" SelectedItem="{Binding RdObj, Mode=TwoWay}" ItemsSource="{Binding RdSource, Mode=TwoWay}"
-                              DisplayMemberPath="Name" TextSearch.TextPath="Name" IsEditable="True"
-                              HorizontalAlignment="Stretch" Margin="0,40,40,10" Grid.Column="1"
-                              SelectionChanged="RdInput_SelectionChanged"/>
-                    <Button x:Name="RdAddButton" Content="&#xE73E;" FontFamily="Segoe MDL2 Assets" FontSize="16" Padding="0,0,0,0" IsEnabled="False"
-                            Click="RdAddButton_Click"
-                            Grid.Column="1" VerticalAlignment="Top" HorizontalAlignment="Right" Width="25" Height="25" Margin="10,40,10,10"/>
+                    <Label Content="Laufzeit:" Margin="10,40,0,0" Grid.Column="0"/>
+                    <TextBox x:Name="YearFromInput" Text="{Binding YearFromString, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
+                             Margin="0,40,10,0" Width="40" HorizontalAlignment="Left" Grid.Column="1" TextAlignment="Right"
+                             TextChanged="IntegerInput_TextChanged"/>
+                    <Label Content="&#x2013;" Grid.Column="1" Margin="45,40,0,0"/>
+                    <TextBox x:Name="YearToInput" Text="{Binding YearToString, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
+                             Margin="60,40,10,0" Width="40" HorizontalAlignment="Left" Grid.Column="1" TextAlignment="Right"
+                             TextChanged="IntegerInput_TextChanged"/>
 
-                    <Label Content="Parzelle(n):" Margin="10,70,0,0" Grid.Column="0"/>
-                    <TextBox x:Name="GstNrInput" Text="{Binding GstNr, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
-                             Margin="0,70,10,0" Grid.Column="1" HorizontalAlignment="Stretch"
-                             TextChanged="TextBox_TextChanged"/>
+                    <Label Content="Vertragsart:" Margin="10,70,0,0" Grid.Column="0"/>
+                    <ComboBox x:Name="AreaComTypeInput" SelectedItem="{Binding AreaComType, Mode=TwoWay}" ItemsSource="{Binding AreaComTypeSource, Mode=TwoWay}"
+                              ItemTemplate="{StaticResource AreaCommitmentTypeTemplate}" TextSearch.TextPath="DisplayName"
+                              HorizontalAlignment="Stretch" Margin="0,70,40,10" Grid.Column="1"/>
+                    <Button x:Name="AreaComTypeDetailsButton" Content="&#xE712;" FontFamily="Segoe MDL2 Assets" FontSize="14" Padding="0,1,0,0"
+                            Click="AreaComTypeDetailsButton_Click"
+                            Grid.Column="3" VerticalAlignment="Top" HorizontalAlignment="Right" Width="25" Height="25" Margin="10,70,10,10"/>
 
-                    <Label Content="Fläche:" Margin="10,100,0,0" Grid.Column="0"/>
+                    <Label Content="Bewirt.-Art:" Margin="10,100,0,0" Grid.Column="0"/>
+                    <ComboBox x:Name="WineCultivationInput" SelectedItem="{Binding WineCultObj, Mode=TwoWay}" ItemsSource="{Binding WineCultSource, Mode=TwoWay}"
+                              DisplayMemberPath="Name" TextSearch.TextPath="Name"
+                              HorizontalAlignment="Stretch" Margin="0,100,10,0" Grid.Column="1"/>
+
+                    <Label Content="Fläche:" Margin="10,130,0,0" Grid.Column="0"/>
                     <ctrl:UnitTextBox x:Name="AreaInput" Unit="m²" Text="{Binding AreaString, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
                                       TextChanged="IntegerInput_TextChanged"
-                                      Grid.Column="1" Width="70" Margin="0,100,10,10" VerticalAlignment="Top" HorizontalAlignment="Left"/>
+                                      Grid.Column="1" Width="70" Margin="0,130,10,10" VerticalAlignment="Top" HorizontalAlignment="Left"/>
+
+                    <Label Content="Parzelle(n):" Margin="10,160,0,0" Grid.Column="0"/>
+                    <TextBox x:Name="GstNrInput" Text="{Binding GstNr, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
+                             Margin="0,160,10,0" Grid.Column="1" HorizontalAlignment="Stretch"
+                             TextChanged="TextBox_TextChanged"/>
                 </Grid>
             </GroupBox>
         </Grid>
diff --git a/Elwig/Windows/AreaComAdminWindow.xaml.cs b/Elwig/Windows/AreaComAdminWindow.xaml.cs
index 8c2d16d..04d5b60 100644
--- a/Elwig/Windows/AreaComAdminWindow.xaml.cs
+++ b/Elwig/Windows/AreaComAdminWindow.xaml.cs
@@ -25,22 +25,21 @@ namespace Elwig.Windows {
             ViewModel.FilterMember = ctx.Members.Find(mgnr) ?? throw new ArgumentException("MgNr argument has invalid value");
             ViewModel.Title = $"Flächenbindungen - {ViewModel.FilterMember.AdministrativeName} - Elwig";
             ExemptInputs = [
-                MgNrInput, AreaCommitmentList, NewAreaCommitmentButton, 
-                EditAreaCommitmentButton, DeleteAreaCommitmentButton, SaveButton,
-                ResetButton, CancelButton, SearchInput, ActiveAreaCommitmentInput
+                AreaCommitmentList, RevisionList,
+                NewAreaCommitmentButton, EditAreaCommitmentButton, DeleteAreaCommitmentButton, SaveButton,
+                ResetButton, CancelButton, SearchInput, SeasonInput
             ];
             RequiredInputs = [
-                FbNrInput, YearFromInput, KgInput, RdInput,
+                FbNrInput, MgNrInput, MemberInput, YearFromInput, KgInput, RdInput,
                 GstNrInput, AreaInput, AreaComTypeInput, WineCultivationInput
             ];
 
             ControlUtils.InitializeDelayTimer(SearchInput, SearchInput_TextChanged);
             SearchInput.TextChanged -= SearchInput_TextChanged;
-            ActiveAreaCommitmentInput.Content = ((string)ActiveAreaCommitmentInput.Content).Replace("2020", $"{Utils.CurrentLastSeason}");
+            ViewModel.FilterSeason = Utils.CurrentYear;
         }
 
         private void Window_Loaded(object sender, RoutedEventArgs e) {
-            ActiveAreaCommitmentInput.IsChecked = true;
             LockInputs();
         }
 
@@ -53,27 +52,34 @@ namespace Elwig.Windows {
 
         private async Task RefreshList(bool updateSort = false) {
             using var ctx = new AppDbContext();
-            var (_, areaComQuery, filter) = await ViewModel.GetFilters(ctx);
+            var (_, contractQuery, areaComQuery, filter) = await ViewModel.GetFilters(ctx);
+            var contracts = await contractQuery
+                .Include(c => c.Kg.AtKg)
+                .Include(c => c.Rd!.Kg.AtKg)
+                .Include(c => c.Revisions).ThenInclude(a => a.WineCult)
+                .Include(c => c.Revisions).ThenInclude(a => a.AreaComType.WineAttr)
+                .Include(c => c.Revisions).ThenInclude(a => a.AreaComType.WineVar)
+                .Include(c => c.Revisions).ThenInclude(a => a.Member)
+                .ToListAsync();
             var areaComs = await areaComQuery
-                .Include(a => a.Kg.AtKg)
-                .Include(a => a.Rd!.Kg.AtKg)
+                .Include(c => c.Contract.Kg.AtKg)
+                .Include(c => c.Contract.Rd!.Kg.AtKg)
                 .Include(a => a.WineCult)
                 .Include(a => a.AreaComType.WineAttr)
                 .Include(a => a.AreaComType.WineVar)
                 .ToListAsync();
 
-            if (filter.Count > 0 && areaComs.Count > 0) {
-                var dict = areaComs.AsParallel()
+            if (filter.Count > 0 && contracts.Count > 0) {
+                var dict = contracts.AsParallel()
                     .ToDictionary(d => d, d => d.SearchScore(ViewModel.TextFilter))
                     .OrderByDescending(c => c.Value);
-                var threshold = dict.Select(a => a.Value).Max() * 3 / 4;
-                areaComs = dict
+                var threshold = dict.Max(a => a.Value) * 3 / 4;
+                contracts = [.. dict
                     .Where(a => a.Value > threshold)
-                    .Select(a => a.Key)
-                    .ToList();
+                    .Select(a => a.Key)];
             }
 
-            ControlUtils.RenewItemsSource(AreaCommitmentList, areaComs,
+            ControlUtils.RenewItemsSource(AreaCommitmentList, contracts,
                 AreaCommitmentList_SelectionChanged, filter.Count > 0 ? ControlUtils.RenewSourceDefault.IfOnly : ControlUtils.RenewSourceDefault.None, !updateSort);
             RefreshInputs();
 
@@ -84,8 +90,8 @@ namespace Elwig.Windows {
                 ViewModel.StatusArea = text;
                 ViewModel.StatusAreaToolTip = AreaComService.GenerateToolTip(gridData);
             } else {
-                ViewModel.StatusAreaCommitments = $"{areaComs.Count:N0}";
-                ViewModel.StatusArea = $"{areaComs.Select(a => a.Area).Sum():N0} m²";
+                ViewModel.StatusAreaCommitments = $"{contracts.Count:N0}";
+                ViewModel.StatusArea = $"{areaComs.Sum(a => a.Area):N0} m²";
                 ViewModel.StatusAreaToolTip = null;
             }
             var groups = areaComs.GroupBy(a => $"{a.AreaComType.SortId}{a.AreaComType.AttrId}").Select(a => (a.Key, a.Sum(b => b.Area))).OrderByDescending(a => a.Item2).ToList();
@@ -94,12 +100,25 @@ namespace Elwig.Windows {
                 ViewModel.StatusContracts += $" ({string.Join(", ", groups.Select(g => g.Key))})";
         }
 
+        private async Task RefreshRevisions() {
+            using var ctx = new AppDbContext();
+            if (AreaCommitmentList.SelectedItem is AreaComContract c) {
+                ControlUtils.RenewItemsSource(RevisionList, c.Revisions.OrderByDescending(p => p.RevNr).ToList(), RevisionList_SelectionChanged, ControlUtils.RenewSourceDefault.First);
+            } else {
+                RevisionList.ItemsSource = null;
+            }
+        }
+
         private void RefreshInputs(bool validate = false) {
             ClearInputStates();
-            if (AreaCommitmentList.SelectedItem is AreaCom a) {
+            if (RevisionList.SelectedItem is AreaCom a) {
                 EditAreaCommitmentButton.IsEnabled = true;
                 DeleteAreaCommitmentButton.IsEnabled = true;
                 FillInputs(a);
+            } else if (AreaCommitmentList.SelectedItem is AreaComContract c) {
+                EditAreaCommitmentButton.IsEnabled = true;
+                DeleteAreaCommitmentButton.IsEnabled = true;
+                FillInputs(c);
             } else {
                 EditAreaCommitmentButton.IsEnabled = false;
                 DeleteAreaCommitmentButton.IsEnabled = false;
@@ -111,7 +130,15 @@ namespace Elwig.Windows {
             GC.Collect();
         }
 
+        private void FillInputs(AreaComContract c) {
+            ClearOriginalValues();
+            ClearDefaultValues();
+            ViewModel.FillInputs(c);
+            FinishInputFilling();
+        }
+
         private void FillInputs(AreaCom a) {
+            FillInputs(a.Contract);
             ClearOriginalValues();
             ClearDefaultValues();
             ViewModel.FillInputs(a);
@@ -146,6 +173,9 @@ namespace Elwig.Windows {
                 .Include(c => c.WineAttr)
                 .OrderBy(v => v.VtrgId)
                 .ToListAsync());
+            ControlUtils.RenewItemsSource(MemberInput, await ctx.Members
+                .OrderBy(m => m.Name).ThenBy(m => m.GivenName).ThenBy(m => m.MgNr)
+                .ToListAsync());
             var cultList = await ctx.WineCultivations
                 .OrderBy(c => c.Name)
                 .Cast<object>().ToListAsync();
@@ -164,6 +194,7 @@ namespace Elwig.Windows {
             IsCreating = true;
             AreaCommitmentList.IsEnabled = false;
             AreaCommitmentList.SelectedItem = null;
+            RevisionList.IsEnabled = false;
             HideNewEditDeleteButtons();
             ShowSaveResetCancelButtons();
             UnlockInputs();
@@ -184,6 +215,7 @@ namespace Elwig.Windows {
 
             IsEditing = true;
             AreaCommitmentList.IsEnabled = false;
+            RevisionList.IsEnabled = false;
 
             HideNewEditDeleteButtons();
             ShowSaveResetCancelButtons();
@@ -198,10 +230,10 @@ namespace Elwig.Windows {
         }
 
         private async void DeleteAreaCommitmentButton_Click(object? sender, RoutedEventArgs? evt) {
-            if (AreaCommitmentList.SelectedItem is not AreaCom a)
+            if (RevisionList.SelectedItem is not AreaCom a)
                 return;
 
-            var d = new AreaComModifyDialog(a.YearFrom, a.YearTo, a.Area, true);
+            var d = new AreaComModifyDialog(a.YearFrom, a.YearTo, a.Area, true, RevisionList.ItemsSource.Cast<object>().FirstOrDefault() != a);
             if (d.ShowDialog() != true)
                 return;
 
@@ -209,7 +241,7 @@ namespace Elwig.Windows {
             try {
                 if (d.YearTo is int yearTo) {
                     ViewModel.YearTo = yearTo;
-                    await ViewModel.UpdateAreaCommitment((AreaCommitmentList.SelectedItem as AreaCom)?.FbNr);
+                    await ViewModel.UpdateAreaCommitment(a.FbNr, a.RevNr);
                 } else {
                     await AreaComService.DeleteAreaCom(a.FbNr);
                 }
@@ -232,42 +264,36 @@ namespace Elwig.Windows {
             SaveButton.IsEnabled = false;
 
             int? yearTo = null;
-            if (InputHasChanged(AreaInput) || InputHasChanged(AreaComTypeInput)) {
-                var a = (AreaCommitmentList.SelectedItem as AreaCom)!;
-                var d = new AreaComModifyDialog(a.YearFrom, a.YearTo, a.Area, false);
+            if (InputHasChanged(AreaInput) || InputHasChanged(AreaComTypeInput) || InputHasChanged(MgNrInput)) {
+                var a = (RevisionList.SelectedItem as AreaCom)!;
+                var d = new AreaComModifyDialog(a.YearFrom, a.YearTo, a.Area, false, RevisionList.ItemsSource.Cast<object>().FirstOrDefault() != a);
                 if (d.ShowDialog() != true)
                     return;
                 yearTo = d.YearTo;
             }
 
-            int fbnr;
+            int fbnr, revnr;
             Mouse.OverrideCursor = Cursors.Wait;
             try {
                 AreaCom? temp = null;
                 if (yearTo != null && (!ViewModel.YearTo.HasValue || yearTo < ViewModel.YearTo)) {
                     temp = new AreaCom {
-                        FbNr = ViewModel.FbNr!.Value,
                         MgNr = ViewModel.MgNr!.Value,
                         YearFrom = ViewModel.YearFrom,
                         YearTo = ViewModel.YearTo,
                         VtrgId = ViewModel.AreaComType!.VtrgId,
                         CultId = ViewModel.WineCult?.CultId,
-                        Comment = ViewModel.Comment,
-                        KgNr = ViewModel.Kg!.KgNr,
-                        RdNr = ViewModel.Rd?.RdNr,
                         GstNr = ViewModel.GstNr?.Trim() ?? "-",
                         Area = ViewModel.Area!.Value,
                     };
                     RefreshInputs();
                     ViewModel.YearTo = yearTo;
                 }
-                fbnr = await ViewModel.UpdateAreaCommitment((AreaCommitmentList.SelectedItem as AreaCom)?.FbNr);
+                (fbnr, revnr) = await ViewModel.UpdateAreaCommitment((AreaCommitmentList.SelectedItem as AreaComContract)?.FbNr, (RevisionList.SelectedItem as AreaCom)?.RevNr);
                 if (temp is AreaCom t) {
-                    await ViewModel.InitInputs();
-                    t.FbNr = ViewModel.FbNr!.Value;
                     t.YearFrom = yearTo + 1;
                     ViewModel.FillInputs(t);
-                    fbnr = await ViewModel.UpdateAreaCommitment(null);
+                    (fbnr, revnr) = await ViewModel.UpdateAreaCommitment((AreaCommitmentList.SelectedItem as AreaComContract)?.FbNr, null);
                 }
                 App.HintContextChange();
             } catch (Exception exc) {
@@ -282,6 +308,7 @@ namespace Elwig.Windows {
             IsEditing = false;
             IsCreating = false;
             AreaCommitmentList.IsEnabled = true;
+            RevisionList.IsEnabled = true;
             HideSaveResetCancelButtons();
             ShowNewEditDeleteButtons();
             LockInputs();
@@ -290,7 +317,9 @@ namespace Elwig.Windows {
             await EnsureContextRenewed();
             Mouse.OverrideCursor = null;
             ViewModel.SearchQuery = "";
-            ControlUtils.SelectItem(AreaCommitmentList, AreaCommitmentList.ItemsSource.Cast<AreaCom>().Where(a => a.FbNr == fbnr).FirstOrDefault());
+            ViewModel.FilterSeason = ViewModel.YearTo ?? ViewModel.YearFrom ?? ViewModel.FilterSeason;
+            ControlUtils.SelectItemWithPk(AreaCommitmentList, fbnr);
+            ControlUtils.SelectItemWithPk(RevisionList, fbnr, revnr);
         }
 
         protected override void ShortcutReset() {
@@ -312,6 +341,7 @@ namespace Elwig.Windows {
             IsEditing = false;
             IsCreating = false;
             AreaCommitmentList.IsEnabled = true;
+            RevisionList.IsEnabled = true;
             HideSaveResetCancelButtons();
             ShowNewEditDeleteButtons();
             RefreshInputs();
@@ -373,22 +403,46 @@ namespace Elwig.Windows {
 
         private void LockSearchInputs() {
             SearchInput.IsEnabled = false;
-            ActiveAreaCommitmentInput.IsEnabled = false;
+            SeasonInput.IsEnabled = false;
         }
 
         private void UnlockSearchInputs() {
             SearchInput.IsEnabled = true;
-            ActiveAreaCommitmentInput.IsEnabled = true;
+            SeasonInput.IsEnabled = true;
         }
 
-        private void AreaCommitmentList_SelectionChanged(object sender, SelectionChangedEventArgs evt) {
+        private async void AreaCommitmentList_SelectionChanged(object sender, SelectionChangedEventArgs evt) {
             if (AreaCommitmentList.SelectedItem != null)
                 AreaCommitmentList.ScrollIntoView(AreaCommitmentList.SelectedItem);
-            RefreshInputs();
+            await RefreshRevisions();
         }
 
-        private void AttributesInput_SelectionChanged(object sender, SelectionChangedEventArgs evt) {
+        private void RevisionList_SelectionChanged(object? sender, SelectionChangedEventArgs? evt) {
+            RefreshInputs();
+            if (RevisionList.SelectedItem is AreaCom c) {
+                EditAreaCommitmentButton.IsEnabled = true;
+            } else {
+                EditAreaCommitmentButton.IsEnabled = false;
+            }
+        }
 
+        private void MgNrInput_TextChanged(object sender, TextChangedEventArgs evt) {
+            var valid = InputTextChanged((TextBox)sender, Validator.CheckMgNr);
+            var text = MgNrInput.Text;
+            var caret = MgNrInput.CaretIndex;
+            ControlUtils.SelectItemWithPk(MemberInput, valid ? ViewModel.MgNr : null);
+            MgNrInput.Text = text;
+            MgNrInput.CaretIndex = caret;
+        }
+
+        private void MgNrInput_LostFocus(object sender, RoutedEventArgs evt) {
+            var valid = InputLostFocus((TextBox)sender, Validator.CheckMgNr);
+            ControlUtils.SelectItemWithPk(MemberInput, valid ? ViewModel.MgNr : null);
+        }
+
+        private void MemberInput_SelectionChanged(object? sender, SelectionChangedEventArgs? evt) {
+            var m = MemberInput.SelectedItem as Member;
+            ViewModel.MgNr = m?.MgNr;
         }
 
         private async void ActiveAreaCommitmentInput_Changed(object sender, RoutedEventArgs evt) {
@@ -401,6 +455,11 @@ namespace Elwig.Windows {
             await RefreshList(true);
         }
 
+        private async void SeasonInput_TextChanged(object sender, TextChangedEventArgs evt) {
+            if (ViewModel.FilterSeason == null) return;
+            await RefreshList();
+        }
+
         private void KgInput_SelectionChanged(object sender, SelectionChangedEventArgs evt) {
             if (KgInput.SelectedItem is AT_Kg kg) {
                 var rdList = kg.WbKg!.Rds.OrderBy(r => r.Name).Cast<object>().ToList();
@@ -438,12 +497,12 @@ namespace Elwig.Windows {
             RdInput.SelectedIndex = s.Count();
         }
 
-        protected void InputTextChanged(TextBox input, Func<TextBox, bool, AreaCom?, ValidationResult> checker) {
-            InputTextChanged(input, checker(input, SenderIsRequired(input), (AreaCom)AreaCommitmentList.SelectedItem));
+        protected void InputTextChanged(TextBox input, Func<TextBox, bool, AreaComContract?, ValidationResult> checker) {
+            InputTextChanged(input, checker(input, SenderIsRequired(input), (AreaComContract)AreaCommitmentList.SelectedItem));
         }
 
-        protected void InputLostFocus(TextBox input, Func<TextBox, bool, AreaCom?, ValidationResult> checker, string? msg = null) {
-            InputLostFocus(input, checker(input, SenderIsRequired(input), (AreaCom)AreaCommitmentList.SelectedItem), msg);
+        protected void InputLostFocus(TextBox input, Func<TextBox, bool, AreaComContract?, ValidationResult> checker, string? msg = null) {
+            InputLostFocus(input, checker(input, SenderIsRequired(input), (AreaComContract)AreaCommitmentList.SelectedItem), msg);
         }
 
         private void FbNrInput_TextChanged(object sender, RoutedEventArgs evt) {
@@ -453,5 +512,10 @@ namespace Elwig.Windows {
         private void FbNrInput_LostFocus(object sender, RoutedEventArgs evt) {
             InputLostFocus((TextBox)sender, Validator.CheckFbNr);
         }
+
+        private void MemberReferenceButton_Click(object sender, RoutedEventArgs evt) {
+            if (MemberInput.SelectedItem is not Member m) return;
+            App.FocusMember(m.MgNr);
+        }
     }
 }
diff --git a/Elwig/Windows/MemberAdminWindow.xaml.cs b/Elwig/Windows/MemberAdminWindow.xaml.cs
index fa6d4a1..e9d37cc 100644
--- a/Elwig/Windows/MemberAdminWindow.xaml.cs
+++ b/Elwig/Windows/MemberAdminWindow.xaml.cs
@@ -796,7 +796,6 @@ namespace Elwig.Windows {
                 if (d.ShowDialog() != true)
                     return;
                 ViewModel.TransferPredecessorAreaComs = d.SuccessorSeason;
-                ViewModel.MaintainAreaComYearFrom = d.MaintainYearFrom;
                 if (IsEditing)
                     SetOriginalValue(PredecessorMgNrInput, -1);  // hack to allow user to save
                 UpdateButtons();
diff --git a/Elwig/Windows/OriginHierarchyWindow.xaml.cs b/Elwig/Windows/OriginHierarchyWindow.xaml.cs
index baa1707..f31bcf5 100644
--- a/Elwig/Windows/OriginHierarchyWindow.xaml.cs
+++ b/Elwig/Windows/OriginHierarchyWindow.xaml.cs
@@ -100,8 +100,8 @@ namespace Elwig.Windows {
                 var allMembers = await ctx.Members.Where(m => m.DefaultKgNr == k.KgNr).CountAsync();
                 StatusDefaultKgs.Text += $"{activeMembers:N0} ({allMembers:N0})";
                 var year = Utils.CurrentNextSeason;
-                var activeAreaComs = await Utils.ActiveAreaCommitments(ctx.AreaCommitments.Where(c => c.KgNr == k.KgNr), year).CountAsync();
-                var allAreaComs = await ctx.AreaCommitments.Where(c => c.KgNr == k.KgNr).CountAsync();
+                var activeAreaComs = await Utils.ActiveAreaCommitments(ctx.AreaCommitments.Where(c => c.Contract.KgNr == k.KgNr), year).CountAsync();
+                var allAreaComs = await ctx.AreaCommitments.Where(c => c.Contract.KgNr == k.KgNr).CountAsync();
                 StatusAreaCommitments.Text += $"{activeAreaComs:N0} ({allAreaComs:N0})";
                 var deliveryParts = await ctx.DeliveryParts.Where(p => p.KgNr == k.KgNr).CountAsync();
                 var deliveries = await ctx.Deliveries.Where(d => d.Parts.Any(p => p.KgNr == k.KgNr)).CountAsync();
diff --git a/Tests/Resources/Sql/BillingDelete.sql b/Tests/Resources/Sql/BillingDelete.sql
index 5215d87..c6a733b 100644
--- a/Tests/Resources/Sql/BillingDelete.sql
+++ b/Tests/Resources/Sql/BillingDelete.sql
@@ -3,7 +3,7 @@
 DELETE FROM credit;
 DELETE FROM payment_variant;
 DELETE FROM delivery;
-DELETE FROM area_commitment;
+DELETE FROM area_commitment_contract;
 DELETE FROM area_commitment_type;
 DELETE FROM season;
 DELETE FROM wine_attribute;
diff --git a/Tests/Resources/Sql/BillingInsert.sql b/Tests/Resources/Sql/BillingInsert.sql
index 0ee9178..2693ec5 100644
--- a/Tests/Resources/Sql/BillingInsert.sql
+++ b/Tests/Resources/Sql/BillingInsert.sql
@@ -22,10 +22,15 @@ INSERT INTO area_commitment_type (vtrgid, sortid, attrid, disc, min_kg_per_ha, p
 ('GVQ', 'GV', 'Q',  NULL, 5000, 1000, 1000000, NULL),
 ('GVR', 'GV', 'R',  NULL, 5000, 1000, 1000000, NULL);
 
-INSERT INTO area_commitment (fbnr, mgnr, vtrgid, cultid, area, kgnr, gstnr, rdnr, year_from, year_to) VALUES
-( 1, 101, 'GV', 'KIP', 10000, 06109, '123/4', NULL, 2000, 2019),
-( 2, 101, 'GV', 'KIP', 10000, 06109, '123/5', NULL, 2025, 2030),
-( 3, 101, 'GV', 'KIP', 10000, 06109, '123/6', NULL, 2021, 2031);
+INSERT INTO area_commitment_contract (fbnr, kgnr, rdnr) VALUES
+( 1, 06109, NULL),
+( 2, 06109, NULL),
+( 3, 06109, NULL);
+
+INSERT INTO area_commitment (fbnr, revnr, mgnr, vtrgid, cultid, area, gstnr, year_from, year_to) VALUES
+( 1, 1, 101, 'GV', 'KIP', 10000, '123/4', 2000, 2019),
+( 2, 1, 101, 'GV', 'KIP', 10000, '123/5', 2025, 2030),
+( 3, 1, 101, 'GV', 'KIP', 10000, '123/6', 2021, 2031);
 
 INSERT INTO season (year, currency, min_kg_per_bs, max_kg_per_bs, penalty_per_kg, penalty_amount, penalty_none, start_date, end_date) VALUES
 (2020, 'EUR', 1000, 2000, NULL, NULL, NULL, NULL, NULL),
diff --git a/Tests/Resources/Sql/ServiceDelete.sql b/Tests/Resources/Sql/ServiceDelete.sql
index 553a721..8611e2c 100644
--- a/Tests/Resources/Sql/ServiceDelete.sql
+++ b/Tests/Resources/Sql/ServiceDelete.sql
@@ -4,7 +4,7 @@ DELETE FROM credit;
 DELETE FROM payment_variant;
 DELETE FROM delivery;
 DELETE FROM season;
-DELETE FROM area_commitment;
+DELETE FROM area_commitment_contract;
 DELETE FROM area_commitment_type;
 DELETE FROM member WHERE mgnr >= 200;
 DELETE FROM wine_cultivation;
diff --git a/Tests/Resources/Sql/ServiceInsert.sql b/Tests/Resources/Sql/ServiceInsert.sql
index c947db7..4bd41d6 100644
--- a/Tests/Resources/Sql/ServiceInsert.sql
+++ b/Tests/Resources/Sql/ServiceInsert.sql
@@ -29,11 +29,17 @@ INSERT INTO member_email_address (mgnr, nr, address, comment) VALUES
 INSERT INTO area_commitment_type (vtrgid, sortid, attrid, disc, min_kg_per_ha, penalty_per_kg, penalty_amount, penalty_none) VALUES
 ('GV', 'GV', NULL, NULL, 5000,  500,    NULL, NULL);
 
-INSERT INTO area_commitment (fbnr, mgnr, vtrgid, cultid, area, kgnr, gstnr, rdnr, year_from, year_to) VALUES
-( 1, 203, 'GV', NULL, 10000, 15224, '321/9', NULL, NULL, NULL),
-( 2, 204, 'GV', NULL, 10000, 15224, '123/1', NULL, 2000, 2019),
-( 3, 204, 'GV', NULL, 10000, 15224, '123/2', NULL, 2025, 2030),
-( 4, 204, 'GV', NULL, 10000, 15224, '123/3', NULL, 2021, 2031);
+INSERT INTO area_commitment_contract (fbnr, kgnr, rdnr) VALUES
+( 1, 15224, NULL),
+( 2, 15224, NULL),
+( 3, 15224, NULL),
+( 4, 15224, NULL);
+
+INSERT INTO area_commitment (fbnr, revnr, mgnr, vtrgid, cultid, area, gstnr, year_from, year_to) VALUES
+( 1, 1, 203, 'GV', NULL, 10000, '321/9', NULL, NULL),
+( 2, 1, 204, 'GV', NULL, 10000, '123/1', 2000, 2019),
+( 3, 1, 204, 'GV', NULL, 10000, '123/2', 2025, 2030),
+( 4, 1, 204, 'GV', NULL, 10000, '123/3', 2021, 2031);
 
 
 INSERT INTO season (year, currency, min_kg_per_bs, max_kg_per_bs, penalty_per_kg, penalty_amount, penalty_none, start_date, end_date) VALUES
diff --git a/Tests/fetch-resources.bat b/Tests/fetch-resources.bat
index 629843d..2b510f9 100644
--- a/Tests/fetch-resources.bat
+++ b/Tests/fetch-resources.bat
@@ -1 +1 @@
-curl --fail -s -L "https://elwig.at/files/create.sql?v=36" -u "elwig:ganzGeheim123!" -o "Resources\Sql\Create.sql"
+curl --fail -s -L "https://elwig.at/files/create.sql?v=38" -u "elwig:ganzGeheim123!" -o "Resources\Sql\Create.sql"