diff --git a/ZB.MOM.WW.OtOpcUa.slnx b/ZB.MOM.WW.OtOpcUa.slnx
index ebe20da3..34b52687 100644
--- a/ZB.MOM.WW.OtOpcUa.slnx
+++ b/ZB.MOM.WW.OtOpcUa.slnx
@@ -30,6 +30,7 @@
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/ZB.MOM.WW.OtOpcUa.Driver.AbCip.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Contracts/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Contracts.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.csproj" />
+    <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.csproj" />
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDataType.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/AbLegacyDataType.cs
similarity index 55%
rename from src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDataType.cs
rename to src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/AbLegacyDataType.cs
index e46283d4..3c066c7e 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDataType.cs
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/AbLegacyDataType.cs
@@ -1,5 +1,3 @@
-using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
-
 namespace ZB.MOM.WW.OtOpcUa.Driver.AbLegacy;
 
 /// <summary>
@@ -27,22 +25,3 @@ public enum AbLegacyDataType
     /// <summary>Control sub-element — caller addresses <c>.LEN</c>, <c>.POS</c>, <c>.EN</c>, <c>.DN</c>, <c>.ER</c>.</summary>
     ControlElement,
 }
-
-/// <summary>Map a PCCC data type to the driver-surface <see cref="DriverDataType"/>.</summary>
-public static class AbLegacyDataTypeExtensions
-{
-    /// <summary>Converts an AbLegacyDataType to the corresponding DriverDataType.</summary>
-    /// <param name="t">The PCCC data type to convert.</param>
-    /// <returns>The mapped driver data type.</returns>
-    public static DriverDataType ToDriverDataType(this AbLegacyDataType t) => t switch
-    {
-        AbLegacyDataType.Bit => DriverDataType.Boolean,
-        AbLegacyDataType.Int or AbLegacyDataType.AnalogInt => DriverDataType.Int32,
-        AbLegacyDataType.Long => DriverDataType.Int32,       // matches Modbus/AbCip 64→32 gap
-        AbLegacyDataType.Float => DriverDataType.Float32,
-        AbLegacyDataType.String => DriverDataType.String,
-        AbLegacyDataType.TimerElement or AbLegacyDataType.CounterElement
-            or AbLegacyDataType.ControlElement => DriverDataType.Int32,
-        _ => DriverDataType.Int32,
-    };
-}
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDriverOptions.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/AbLegacyDriverOptions.cs
similarity index 96%
rename from src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDriverOptions.cs
rename to src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/AbLegacyDriverOptions.cs
index 37f12515..81513274 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDriverOptions.cs
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/AbLegacyDriverOptions.cs
@@ -30,7 +30,7 @@ public sealed record AbLegacyDeviceOptions(
 
 /// <summary>
 ///     One PCCC-backed OPC UA variable. <paramref name="Address"/> is the canonical PCCC
-///     file-address string that parses via <see cref="AbLegacyAddress.TryParse"/>.
+///     file-address string that parses via <c>AbLegacyAddress.TryParse</c>.
 /// </summary>
 public sealed record AbLegacyTagDefinition(
     string Name,
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/PlcFamilies/AbLegacyPlcFamilyProfile.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/AbLegacyPlcFamilyProfile.cs
similarity index 100%
rename from src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/PlcFamilies/AbLegacyPlcFamilyProfile.cs
rename to src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/AbLegacyPlcFamilyProfile.cs
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts.csproj b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts.csproj
new file mode 100644
index 00000000..d911061a
--- /dev/null
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts.csproj
@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+    <PropertyGroup>
+        <TargetFramework>net10.0</TargetFramework>
+        <Nullable>enable</Nullable>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    </PropertyGroup>
+    <!-- NO PackageReference. -->
+</Project>
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDataTypeExtensions.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDataTypeExtensions.cs
new file mode 100644
index 00000000..88ea2c33
--- /dev/null
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDataTypeExtensions.cs
@@ -0,0 +1,22 @@
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.AbLegacy;
+
+/// <summary>Map a PCCC data type to the driver-surface <see cref="DriverDataType"/>.</summary>
+public static class AbLegacyDataTypeExtensions
+{
+    /// <summary>Converts an AbLegacyDataType to the corresponding DriverDataType.</summary>
+    /// <param name="t">The PCCC data type to convert.</param>
+    /// <returns>The mapped driver data type.</returns>
+    public static DriverDataType ToDriverDataType(this AbLegacyDataType t) => t switch
+    {
+        AbLegacyDataType.Bit => DriverDataType.Boolean,
+        AbLegacyDataType.Int or AbLegacyDataType.AnalogInt => DriverDataType.Int32,
+        AbLegacyDataType.Long => DriverDataType.Int32,       // matches Modbus/AbCip 64→32 gap
+        AbLegacyDataType.Float => DriverDataType.Float32,
+        AbLegacyDataType.String => DriverDataType.String,
+        AbLegacyDataType.TimerElement or AbLegacyDataType.CounterElement
+            or AbLegacyDataType.ControlElement => DriverDataType.Int32,
+        _ => DriverDataType.Int32,
+    };
+}
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.csproj b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.csproj
index 22df544c..167eb613 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.csproj
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.csproj
@@ -13,6 +13,7 @@
     </PropertyGroup>
 
     <ItemGroup>
+        <ProjectReference Include="..\ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts\ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts.csproj"/>
         <ProjectReference Include="..\..\Core\ZB.MOM.WW.OtOpcUa.Core.Abstractions\ZB.MOM.WW.OtOpcUa.Core.Abstractions.csproj"/>
         <ProjectReference Include="..\..\Core\ZB.MOM.WW.OtOpcUa.Core\ZB.MOM.WW.OtOpcUa.Core.csproj"/>
     </ItemGroup>