Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Visual and Verbal Communication (hierarchy name)
4. Information Forms (hierarchy name)
5. information forms (objects)
6. document genres
7. [documents by function]
8. [identifying markings and symbols]
9. marks (identifying markings)
10. [marks by function]
11. cancellation marks

Anotations

Scope note:

Defacements made by authorities for the primary purpose of preventing reuse of postage stamps; for official marks bearing information about the time and place that a postal system accepted custody of a piece of mail, use "postmarks."