Updated doc comments.

src/Compilers/Core/Portable/Operations/IMultiVariableDeclaration.cs

@@ -9,9 +9,16 @@ namespace Microsoft.CodeAnalysis.Semantics
     /// </summary>
     /// <para>
     /// Current Usage:
-    ///   (1) VB As New statements
-    ///   (2) VB multiple declarations in a single declarator
+    ///   (1) VB Dim statement declaration groups
+    ///   (2) VB Using statement variable declarations
     /// </para>
+    /// <remarks>
+    /// The initializer of this node is applied to all individual declarations in <see cref="Declarations"/>. There cannot
+    /// be initializers in both locations except in invalid code scenarios.
+    ///
+    /// This interface is reserved for implementation by its associated APIs. We reserve the right to
+    /// change it in the future.
+    /// </remarks>
     public interface IMultiVariableDeclaration : IVariableDeclaration
     {
         /// <summary>

src/Compilers/Core/Portable/Operations/ISingleVariableDeclaration.cs

@@ -8,9 +8,13 @@ namespace Microsoft.CodeAnalysis.Semantics
     /// <para>
     /// Current Usage:
     ///   (1) C# variable declarator
-    ///   (2) VB single variable declaration
+    ///   (2) C# catch variable declaration
+    ///   (3) VB single variable declaration
+    ///   (4) VB catch variable declaration
     /// </para>
     /// <remarks>
+    /// In VB, the initializer for this node is only ever used for explicit array bounds initializers.
+    ///
     /// This interface is reserved for implementation by its associated APIs. We reserve the right to
     /// change it in the future.
     /// </remarks>

src/Compilers/Core/Portable/Operations/IVariableDeclarationGroup.cs

@@ -9,8 +9,11 @@ namespace Microsoft.CodeAnalysis.Semantics
     /// </summary>
     /// <para>
     /// Current Usage:
-    ///   (1) C# Local declaration statement
-    ///   (2) VB Dim statement
+    ///   (1) C# local declaration statement
+    ///   (2) C# fixed statement
+    ///   (3) C# using statement
+    ///   (4) VB Dim statement
+    ///   (5) VB Using statement
     /// </para>
     /// <remarks>
     /// This interface is reserved for implementation by its associated APIs. We reserve the right to