Hierarchical Music Specification Language
(HMSL) A programming language for experimental music composition and performance. It is a set of object-oriented extensions to Forth. (Its near-total unintelligibility to people unfamiliar with Forth has led some to expand "HMSL" as "Her Majesty's Secret Language".)
Phil Burk (who also later developed pForth), Larry Polansky, and David Rosenboom started developing HMSL in 1980 while working at the Mills College Center for Contemporary Music. As of June 1998, development is ongoing.