MacGreek
From Just Solve the File Format Problem
MacGreek is Greek to me (and to everyone else); it is a character encoding used on classic Mac OS, encoding the Greek alphabet in the upper section of the 8-bit encoding, with ASCII characters in the lower section.
Some other characters such as accented Roman letters are also included, including the "sharp S" which some mistake for a Greek beta (it isn't; the beta, in upper and lowercase versions, is elsewhere in the encoding).
See Macintosh encodings for related encodings.
