You will most likely see this naming style in the following places:
: The game or software is the version released for the North American market (NTSC-U). (USA) (v1.00)
: Sites like GameFAQs or Archive.org use these tags to distinguish between the original 1.0 release and later "Greatest Hits" or "Platinum" revisions. You will most likely see this naming style
: Tools like the Pikmin 1 Randomizer require specific versions (like USA v1.00) because memory addresses for cheats and mods change between regional and versioned updates. (USA) (v1.00)