diff --git a/src/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/FocasCapabilityMatrix.cs b/src/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/FocasCapabilityMatrix.cs
index 8d84b49..36ba82b 100644
--- a/src/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/FocasCapabilityMatrix.cs
+++ b/src/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/FocasCapabilityMatrix.cs
@@ -97,11 +97,12 @@ public static class FocasCapabilityMatrix
         _ => (0, int.MaxValue),
     };
 
-    /// <summary>PMC letters accepted per series. Legacy controllers omit F/M/C
-    /// signal groups that 30i-family ladder programs use.</summary>
+    /// <summary>PMC letters accepted per series. Legacy 16i ladders use X/Y/F/G
+    /// for handshakes plus R/D for retained/data; M/C/E/A/K/T are the 0i-F /
+    /// 30i-family extensions.</summary>
     internal static IReadOnlySet<string> PmcLetters(FocasCncSeries series) => series switch
     {
-        FocasCncSeries.Sixteen_i     => new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "X", "Y", "R", "D" },
+        FocasCncSeries.Sixteen_i     => new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "X", "Y", "F", "G", "R", "D" },
         FocasCncSeries.Zero_i_D      => new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "X", "Y", "R", "D", "E", "A" },
         FocasCncSeries.Zero_i_F or
         FocasCncSeries.Zero_i_MF or
diff --git a/tests/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests/FocasCapabilityMatrixTests.cs b/tests/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests/FocasCapabilityMatrixTests.cs
index 8efff33..fb5a86a 100644
--- a/tests/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests/FocasCapabilityMatrixTests.cs
+++ b/tests/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests/FocasCapabilityMatrixTests.cs
@@ -57,8 +57,9 @@ public sealed class FocasCapabilityMatrixTests
     [InlineData(FocasCncSeries.Sixteen_i,  "X", true)]
     [InlineData(FocasCncSeries.Sixteen_i,  "Y", true)]
     [InlineData(FocasCncSeries.Sixteen_i,  "R", true)]
-    [InlineData(FocasCncSeries.Sixteen_i,  "F", false)]  // 16i has no F/G signal groups
-    [InlineData(FocasCncSeries.Sixteen_i,  "G", false)]
+    [InlineData(FocasCncSeries.Sixteen_i,  "F", true)]   // #265: F/G handshakes are documented on 16i ladders
+    [InlineData(FocasCncSeries.Sixteen_i,  "G", true)]
+    [InlineData(FocasCncSeries.Sixteen_i,  "M", false)]  // M/C/K/T still 0i-F / 30i-only
     [InlineData(FocasCncSeries.Sixteen_i,  "K", false)]
     [InlineData(FocasCncSeries.Zero_i_D,   "E", true)]   // widened since 0i-D
     [InlineData(FocasCncSeries.Zero_i_D,   "F", false)]  // still no F on 0i-D