Annotations and freehand shapes
There are some types of shape which let you annotate shapes on diagrams. They include text annotation, callout and freehand shape.
A standard UML notation for commenting purpose.
A speech-bubble like shape made for annotation purpose. It's pointer can be adjusted to point to specific position.
A set of shapes that can be bended to different styles to fit in different ways of annotation.
11. Selecting contained shapes with InstantFreeze | Table of Contents | 1. UML note |