1. A tool to annotate items in the hierarchical product structure was added. The tool is located under
fixed label 0:1:9. It operates two basic entities: notes and annotations located under 0:1:9:1 and 0:1:9:2
hives correspondingly. A note is an attribute derived from base class XCAFDoc_Note that is attached to a separate
label under the notes hive. An annotated item is represented by XCAFDoc_AssemblyItemRef attribute
attached to a separate label under the annotated items hive. Notes are linked to annotated items by means of
XCAFDoc_GraphNode attribute, where notes play parent roles and annotated items - child roles.
2. XCAFDoc_AssemblyItemRef defines a weak reference to a label with optional attribute GUID or sub-shape index.
3. A capability to store note/annotation labels in XCAFDoc_ViewTool was added.
4. XDE User guide was updated
