--- a/jvmci/jdk.vm.ci.code/src/jdk/vm/ci/code/site/Mark.java	Thu May 12 11:06:49 2016 +0200
+++ b/jvmci/jdk.vm.ci.code/src/jdk/vm/ci/code/site/Mark.java	Thu May 12 20:57:31 2016 +0200
@@ -25,13 +25,23 @@
 import java.util.Objects;
 
 /**
- * Represents a mark in the machine code that can be used by the runtime for its own purposes. A
- * mark can reference other marks.
+ * Associates arbitrary information with a position in machine code. For example, HotSpot specific
+ * code in a compiler backend may use this to denote the position of a safepoint, exception handler
+ * entry point, verified entry point etc.
  */
 public final class Mark extends Site {
 
+    /**
+     * An object denoting extra semantic information about the machine code position of this mark.
+     */
     public final Object id;
 
+    /**
+     * Creates a mark that associates {@code id} with the machine code position {@code pcOffset}.
+     *
+     * @param pcOffset
+     * @param id
+     */
     public Mark(int pcOffset, Object id) {
         super(pcOffset);
         this.id = id;
@@ -40,7 +50,7 @@
     @Override
     public String toString() {
         if (id == null) {
-            return String.format("%d[<mar>]", pcOffset);
+            return String.format("%d[<mark>]", pcOffset);
         } else if (id instanceof Integer) {
             return String.format("%d[<mark with id %s>]", pcOffset, Integer.toHexString((Integer) id));
         } else {