There is no proper abbreviation for the word global. It is often symbolized by a letter G in acronyms. As far as an abbreviation goes, many people use Gl., but this is in no way a proper abbreviation.
there is no abbreviation
The accepted abbreviation is Depr.
Mr. is the abbreviation for the proper noun Mister, a title. Proper nouns are always capitalized, as well as the abbreviation for a proper noun.
The abbreviation for the word,"VERSION" is V.
A or AA
It's four letters, it needs no abbreviation. Write it.