Trim the S-100 backslashes from the subfield label before a repeating group

Directory.Packages.props

@@ -13,7 +13,7 @@
   <PackageVersion Include="coverlet.collector" Version="6.0.4" />
   <PackageVersion Include="Mapsui.Avalonia" Version="5.0.2" />
   <PackageVersion Include="Mapsui.Nts" Version="5.0.2" />
-  <PackageVersion Include="MessagePack" Version="3.1.8" />
+  <PackageVersion Include="MessagePack" Version="3.1.9" />
   <PackageVersion Include="Microsoft.Extensions.DependencyInjection" Version="10.0.3" />
   <PackageVersion Include="Microsoft.Extensions.Logging" Version="10.0.3" />
   <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="9.0.0" />

src/EncDotNet.Iso8211/Iso8211DataDescriptiveRecordReader.cs

@@ -366,7 +366,8 @@ private static void ParseSubfieldLabels(
                 int starIndex = rawName.IndexOf('*');
                 if (starIndex > 0)
                 {
-                    string leaderName = rawName.Substring(0, starIndex);
+                    // S-100 Part 10a writes "\\" just before the '*'; it is not part of the label.
+                    string leaderName = TrimLabel(rawName.Substring(0, starIndex));
                     if (!string.IsNullOrEmpty(leaderName))
                     {
                         names.Add(leaderName);
@@ -378,6 +379,7 @@ private static void ParseSubfieldLabels(
                 }
             }
 
+            rawName = TrimLabel(rawName);
             if (!string.IsNullOrEmpty(rawName))
             {
                 names.Add(rawName);
@@ -388,6 +390,11 @@ private static void ParseSubfieldLabels(
         subfieldNames = names.ToImmutable();
     }
 
+    /// <summary>
+    /// Removes the trailing backslashes S-100 Part 10a places before a repeating-group <c>*</c>.
+    /// </summary>
+    private static string TrimLabel(string label) => label.TrimEnd('\\');
+
     /// <summary>
     /// Parses the descriptor portion of a DDR field into a field name and subfield names.
     /// </summary>
@@ -439,6 +446,7 @@ private static void ParseDescriptors(
                 rawName = rawName.Substring(1);
             }
 
+            rawName = TrimLabel(rawName);
             if (!string.IsNullOrEmpty(rawName))
             {
                 names.Add(rawName);

tests/EncDotNet.UnitTests/Iso8211DataDescriptiveRecordReaderTests.cs

@@ -1528,6 +1528,55 @@ public void Parse_TwoUtFormat_ConcatenatedArrayWithLeaderAndRepeating_ParsesCorr
         Assert.True(c3il.SubfieldDefinitions[3].IsRepeating);
     }
 
+    [Fact]
+    public void Parse_TwoUtFormat_S100BackslashesBeforeStar_AreTrimmedFromLeaderName()
+    {
+        // Arrange — S-100 Part 10a writes "\\" before the '*' that starts the repeating group
+        // (S-101 2.0 DSID descriptor).
+        var record = CreateDdrRecordTwoUt(
+            tag: "DSID",
+            dataStructureCode: '1',
+            dataTypeCode: '6',
+            fieldName: "Dataset Identification",
+            subfieldLabels: @"RCNM!RCID!ENSP!ENED!PRSP!PRED!PROF!DSNM!DSTL!DSRD!DSLG!DSAB!DSED\\*DSTC",
+            formatControls: "(b11,b14,11A,b11)");
+
+        // Act
+        var ddr = Iso8211DataDescriptiveRecordReader.Read(record);
+        var dsid = ddr.FieldDefinitions[0];
+
+        // Assert
+        Assert.Equal(14, dsid.SubfieldDefinitions.Count);
+        Assert.Equal("DSED", dsid.SubfieldDefinitions[12].Name);
+        Assert.Equal("DSTC", dsid.SubfieldDefinitions[13].Name);
+        Assert.Equal(13, dsid.RepeatingSubfieldStartIndex);
+        Assert.False(dsid.SubfieldDefinitions[12].IsRepeating);
+        Assert.True(dsid.SubfieldDefinitions[13].IsRepeating);
+    }
+
+    [Fact]
+    public void Parse_TwoUtFormat_S100BackslashesBeforeStar_SingleLeaderSubfield()
+    {
+        // Arrange — S-101 2.0 C3IL descriptor
+        var record = CreateDdrRecordTwoUt(
+            tag: "C3IL",
+            dataStructureCode: '3',
+            dataTypeCode: '5',
+            fieldName: "3-D Integer Coordinate List",
+            subfieldLabels: @"VCID\\*YCOO!XCOO!ZCOO",
+            formatControls: "(b11,3b24)");
+
+        // Act
+        var ddr = Iso8211DataDescriptiveRecordReader.Read(record);
+        var c3il = ddr.FieldDefinitions[0];
+
+        // Assert
+        Assert.Equal(4, c3il.SubfieldDefinitions.Count);
+        Assert.Equal("VCID", c3il.SubfieldDefinitions[0].Name);
+        Assert.Equal("YCOO", c3il.SubfieldDefinitions[1].Name);
+        Assert.Equal(1, c3il.RepeatingSubfieldStartIndex);
+    }
+
     [Fact]
     public void Parse_TwoUtFormat_VectorStyleStarAtStart_StillWorks()
     {