ANSI is an acronym referring to the America National Standard Institute but is also the name of a particular font rendering used on the original MS-DOS computer. This term is also used in Unix systems like Linux.
ANSI font is often referred to as extended ASCII and may be used in Text files for an extended text format to support non-English languages. The characters from 32 to 128 are identical with ASCII text. This name can also be used as an alternative to Unicode and can any arbitrary designation of an 8 bit font set (codepage) with the specific set defined later. The term ANSI refers to the fact that Microsoft submitted these code pages to the ANSI committee, but they were never ratified.
 See also
- https://ansi.org/ if you were looking for the standard.