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 form]
8. electronic documents
9. software
10. operating systems
11. [operating systems by specific type]

Anotations

Scope note:

General name for a number of computer operating systems for personal computers; several unrelated microcomputer disk operating systems had "DOS" in their names. An example was MS-DOS, which dominated the IBM PC-compatible market between 1981 and 1995.