diff --git a/jetty-server/src/main/java/org/eclipse/jetty/server/MultiPartFormInputStream.java b/jetty-server/src/main/java/org/eclipse/jetty/server/MultiPartFormInputStream.java
index 5d8eaffaa4ac..063b64ae6e4e 100644
--- a/jetty-server/src/main/java/org/eclipse/jetty/server/MultiPartFormInputStream.java
+++ b/jetty-server/src/main/java/org/eclipse/jetty/server/MultiPartFormInputStream.java
@@ -60,6 +60,13 @@
  * is done by the parsing thread.
  * </p>
  * <pre>{@code
+ *
+ * UNPARSED - Parsing has not started, there are no parts which need to be cleaned up.
+ * PARSING  - The parsing thread is reading from the InputStream and generating parts.
+ * PARSED   - Parsing has complete and no more parts will be generated.
+ * ERROR    - deleteParts() has been called while we were in parsing state.
+ * DELETED  - The parts have been deleted, this is the terminal state.
+ *
  *                              deleteParts()
  *     +--------------------------------------------------------------+
  *     |                                                              |