Windows encodings refers to the various legacy character encodings used by the non-Unicode Microsoft Windows API, and most non-Unicode-aware Windows applications. (GUI applications, anyway. Windows console applications default to using the MS-DOS encodings in many cases.)
In Windows jargon, these encodings are misleadingly called "ANSI", or in some cases (also somewhat misleadingly), "multi-byte" encodings.
All too many file formats use one of these encodings, with no reliable way to determine which one.