Write a musical score even with non-standard notation, using LilyPond

LilyPond is an Open Source engraving system that formats music beautifully and automatically, using a friendly syntax for its input files. It will make your computer printout look just as good as traditionally engraved music.

Features: Allows MusicXML import; church modes support; support for harp pedal diagrams; 64 bit integers for rational numbers, which allows the typesetting of more complex polymetric music.

Note also that with its ASCII interface and flexible design, LilyPond is uniquely suited for various modern music and non-standard notation.

If you don’t find LilyPond convenient, try instead MuseScore, better in many ways.