Vorbis comment
The tagging format normally used by Ogg Vorbis and FLAC is called "vorbis comment". It is a relatively simple format that allows the user to specify arbitrary name/value pairs, using UTF-8 as the character encoding.
To avoid incompatibilities between tags some standard fieldnames are suggested by the vorbis comment specification (TITLE, VERSION, ALBUM, ARTIST, TRACKNUMBER, etc.). The full vorbis comment specification can be found at http://www.xiph.org/vorbis/doc/v-comment.html.