diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTCompoundStatementExpression.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTCompoundStatementExpression.java
index 9e4fe3058db..622fc72b92d 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTCompoundStatementExpression.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTCompoundStatementExpression.java
@@ -14,12 +14,34 @@ import org.eclipse.cdt.core.dom.ast.IASTCompoundStatement;
 import org.eclipse.cdt.core.dom.ast.IASTExpression;
 
 /**
+ * There are GNU language extensions that apply to both GCC and G++. Compound
+ * statement's as expressions.
+ * 
  * @author jcamelon
  */
 public interface IGNUASTCompoundStatementExpression extends IASTExpression {
 
-    public static final ASTNodeProperty STATEMENT = new ASTNodeProperty( "Statement"); //$NON-NLS-1$
-    public IASTCompoundStatement getCompoundStatement();
-    public void setCompoundStatement( IASTCompoundStatement statement );
-    
+	/**
+	 * <code>STATEMENT</code> describes the relationship between
+	 * <code>IGNUASTCompoundStatementExpression</code> and
+	 * <code>IASTCompoundStatement</code>.
+	 */
+	public static final ASTNodeProperty STATEMENT = new ASTNodeProperty(
+			"Statement"); //$NON-NLS-1$
+
+	/**
+	 * Get the compound statement.
+	 * 
+	 * @return <code>IASTCompoundStatement</code>
+	 */
+	public IASTCompoundStatement getCompoundStatement();
+
+	/**
+	 * Set the compound statement.
+	 * 
+	 * @param statement
+	 *            <code>IASTCompoundStatement</code>
+	 */
+	public void setCompoundStatement(IASTCompoundStatement statement);
+
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTTypeIdExpression.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTTypeIdExpression.java
index 8aff26afe4d..cb3d8885ad6 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTTypeIdExpression.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTTypeIdExpression.java
@@ -12,12 +12,27 @@ package org.eclipse.cdt.core.dom.ast.gnu;
 import org.eclipse.cdt.core.dom.ast.IASTTypeIdExpression;
 
 /**
+ * There are GNU language extensions that apply to both GCC and G++. Unary
+ * expressions for _alignOf() and typeof() along the lines of sizeof().
+ * 
  * @author jcamelon
  */
 public interface IGNUASTTypeIdExpression extends IASTTypeIdExpression {
 
-    public static final int op_typeof = IASTTypeIdExpression.op_last + 1;
-    public static final int op_alignof = IASTTypeIdExpression.op_last + 2;
-    public static final int op_last   = op_alignof;
-    
+	/**
+	 * <code>op_typeof</code> is used for typeof( typeId ) type expressions.
+	 */
+	public static final int op_typeof = IASTTypeIdExpression.op_last + 1;
+
+	/**
+	 * <code>op_alignOf</code> is used for __alignOf( typeId ) type
+	 * expressions.
+	 */
+	public static final int op_alignof = IASTTypeIdExpression.op_last + 2;
+
+	/**
+	 * <code>op_last</code> is available for sub-interfaces.
+	 */
+	public static final int op_last = op_alignof;
+
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTUnaryExpression.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTUnaryExpression.java
index 3b7704d32bc..a2f1a93f54d 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTUnaryExpression.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/gnu/IGNUASTUnaryExpression.java
@@ -12,11 +12,27 @@ package org.eclipse.cdt.core.dom.ast.gnu;
 import org.eclipse.cdt.core.dom.ast.IASTUnaryExpression;
 
 /**
+ * There are GNU language extensions that apply to both GCC and G++. Unary
+ * expressions for _alignOf() and typeof() along the lines of sizeof().
+ * 
  * @author jcamelon
  */
 public interface IGNUASTUnaryExpression extends IASTUnaryExpression {
 
-    public static final int op_typeof = IASTUnaryExpression.op_last + 1;
-    public static final int op_alignOf = IASTUnaryExpression.op_last + 2;
-    public static final int op_last = op_alignOf;
+	/**
+	 * <code>op_typeof</code> is used for typeof( unaryExpression ) type
+	 * expressions.
+	 */
+	public static final int op_typeof = IASTUnaryExpression.op_last + 1;
+
+	/**
+	 * <code>op_alignOf</code> is used for __alignOf( unaryExpression ) type
+	 * expressions.
+	 */
+	public static final int op_alignOf = IASTUnaryExpression.op_last + 2;
+
+	/**
+	 * <code>op_last</code> is available for sub-interfaces.
+	 */
+	public static final int op_last = op_alignOf;
 }