diff --git a/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Core/ManualAnnotationPersistence.cs b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Core/ManualAnnotationPersistence.cs
new file mode 100644
index 0000000..d1713a4
--- /dev/null
+++ b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Core/ManualAnnotationPersistence.cs
@@ -0,0 +1,15 @@
+namespace PRecAnnot.Core;
+
+public sealed record ManualAnnotationState(string Kind, ManualDatumMode DatumMode, double DatumOffset)
+{
+    public string Serialize() => string.Join("|", Kind, DatumMode, DatumOffset.ToString(System.Globalization.CultureInfo.InvariantCulture));
+
+    public static ManualAnnotationState? Deserialize(string? value)
+    {
+        if (string.IsNullOrWhiteSpace(value)) return null;
+        var fields = value.Split('|');
+        if (fields.Length != 3 || !Enum.TryParse<ManualDatumMode>(fields[1], true, out var mode) ||
+            !double.TryParse(fields[2], System.Globalization.NumberStyles.Float, System.Globalization.CultureInfo.InvariantCulture, out var offset)) return null;
+        return new ManualAnnotationState(fields[0], mode, offset);
+    }
+}
diff --git a/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/EntryPoint.cs b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/EntryPoint.cs
index 406e2da..460e67a 100644
--- a/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/EntryPoint.cs
+++ b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/EntryPoint.cs
@@ -58,7 +58,7 @@ public sealed class EntryPoint : IExtensionApplication
     [CommandMethod("mto-ma")] public void ShowManualAnnotationPaletteCommand() => ManualAnnotationPalette.Show();
     [CommandMethod("PXP-MA")] public void ShowManualAnnotationPaletteAliasCommand() => ManualAnnotationPalette.Show();
     [CommandMethod("CAC1")] public void PlaceManualAnnotationCommand() => ManualAnnotationPalette.PlaceSelected();
-    [CommandMethod("PXP-MAB")] public void InsertManualBlockCommand() => ManualBlockInsertionCommand.Run();
+    [CommandMethod("PXP-MAB")] public void InsertManualBlockCommand() => ManualBlockInsertionCommand.Run(ManualAnnotationPalette.CurrentState());
 
     [CommandMethod("PHP_REC_AUTOMATION_START", CommandFlags.Session)]
     public void AutomationStartCommand() => FirstLimitedApplyAutomationBootstrap.Arm();
diff --git a/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/ManualAnnotationPalette.cs b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/ManualAnnotationPalette.cs
index ae7909a..0b876f1 100644
--- a/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/ManualAnnotationPalette.cs
+++ b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/ManualAnnotationPalette.cs
@@ -38,6 +38,7 @@ internal static class ManualAnnotationPalette
         RuntimeDiagnostics.Write("ManualAnnotationPaletteShown", resultStatus: "Visible");
     }
     public static void PlaceSelected() => control?.Place();
+    public static ManualAnnotationState CurrentState() => control?.CurrentState() ?? new ManualAnnotationState("AutoCadBlock", ManualDatumMode.Absolute, 0);
     private static void DocumentActivated(object sender, Autodesk.AutoCAD.ApplicationServices.DocumentCollectionEventArgs args) => control?.RefreshAvailability();
 }
 
@@ -74,6 +75,7 @@ internal sealed class ManualAnnotationControl : WinForms.UserControl
         document.SendStringToExecute(command + " ", true, false, false);
         RuntimeDiagnostics.Write("ManualAnnotationActionInvoked", commandName: command, resultStatus: kind.ToString(), document: document);
     }
+    public ManualAnnotationState CurrentState() => new(kinds.First(value => value.Key.Checked).Value.ToString(), relativeDatum.Checked ? ManualDatumMode.Relative : ManualDatumMode.Absolute, (double)datumOffset.Value);
     private static void Reconnect() => AcadApplication.DocumentManager.MdiActiveDocument?.SendStringToExecute("PXP-ULN ", true, false, false);
     private static void OpenHelp()
     {
@@ -90,7 +92,7 @@ internal sealed class ManualAnnotationControl : WinForms.UserControl
 
 internal static class ManualBlockInsertionCommand
 {
-    public static void Run()
+    public static void Run(ManualAnnotationState state)
     {
         var document = AcadApplication.DocumentManager.MdiActiveDocument; if (document is null) return;
         var name = document.Editor.GetString(new PromptStringOptions("\nBlock name: ") { AllowSpaces = true }); if (name.Status != PromptStatus.OK || string.IsNullOrWhiteSpace(name.StringResult)) return;
@@ -99,7 +101,12 @@ internal static class ManualBlockInsertionCommand
         using var documentLock = document.LockDocument(); using var transaction = document.Database.TransactionManager.StartTransaction();
         var blocks = (BlockTable)transaction.GetObject(document.Database.BlockTableId, OpenMode.ForRead); if (!blocks.Has(name.StringResult)) { document.Editor.WriteMessage("\nBlock definition not found."); return; }
         var space = (BlockTableRecord)transaction.GetObject(document.Database.CurrentSpaceId, OpenMode.ForWrite); var definition = (BlockTableRecord)transaction.GetObject(blocks[name.StringResult], OpenMode.ForRead);
-        using var reference = new BlockReference(point.Value, definition.ObjectId) { Rotation = angle.Status == PromptStatus.OK ? angle.Value : 0 }; space.AppendEntity(reference); transaction.AddNewlyCreatedDBObject(reference, true);
+        using var reference = new BlockReference(point.Value, definition.ObjectId) { Rotation = angle.Status == PromptStatus.OK ? angle.Value : 0 };
+        space.AppendEntity(reference); transaction.AddNewlyCreatedDBObject(reference, true);
+        var regApps = (RegAppTable)transaction.GetObject(document.Database.RegAppTableId, OpenMode.ForRead);
+        const string appName = "P_REC_ANNOT_MANUAL";
+        if (!regApps.Has(appName)) { regApps.UpgradeOpen(); using var app = new RegAppTableRecord { Name = appName }; regApps.Add(app); transaction.AddNewlyCreatedDBObject(app, true); }
+        reference.XData = new ResultBuffer(new TypedValue((int)DxfCode.ExtendedDataRegAppName, appName), new TypedValue((int)DxfCode.ExtendedDataAsciiString, state.Serialize()));
         foreach (ObjectId id in definition)
             if (transaction.GetObject(id, OpenMode.ForRead) is AttributeDefinition source && !source.Constant)
             { var value = document.Editor.GetString(new PromptStringOptions($"\n{source.Tag} <{source.TextString}>: ") { AllowSpaces = true }); using var attribute = new AttributeReference(); attribute.SetAttributeFromBlock(source, reference.BlockTransform); attribute.TextString = value.Status == PromptStatus.OK ? value.StringResult : source.TextString; reference.AttributeCollection.AppendAttribute(attribute); transaction.AddNewlyCreatedDBObject(attribute, true); }
diff --git a/Plant3D2026/P_Rec_Annot/tests/PRecAnnot.Core.Tests/ManualAnnotationPersistenceTests.cs b/Plant3D2026/P_Rec_Annot/tests/PRecAnnot.Core.Tests/ManualAnnotationPersistenceTests.cs
new file mode 100644
index 0000000..089e68a
--- /dev/null
+++ b/Plant3D2026/P_Rec_Annot/tests/PRecAnnot.Core.Tests/ManualAnnotationPersistenceTests.cs
@@ -0,0 +1,20 @@
+using PRecAnnot.Core;
+
+namespace PRecAnnot.Core.Tests;
+
+public sealed class ManualAnnotationPersistenceTests
+{
+    [Theory]
+    [InlineData("AutoCadBlock", ManualDatumMode.Absolute, 0)]
+    [InlineData("SectionElevation", ManualDatumMode.Relative, -12.5)]
+    [InlineData("InstrumentPosition", ManualDatumMode.Relative, 4.25)]
+    public void State_round_trips_without_losing_legacy_datum_values(string kind, ManualDatumMode mode, double offset)
+    {
+        var state = new ManualAnnotationState(kind, mode, offset);
+        var restored = ManualAnnotationState.Deserialize(state.Serialize());
+        Assert.Equal(state, restored);
+    }
+
+    [Fact]
+    public void Invalid_state_is_not_accepted() => Assert.Null(ManualAnnotationState.Deserialize("bad|payload"));
+}