command-line tool to typeset Gregorian chant

 Gregorio is a project with a lot of functionalities. The main interest is gabc,
 a very simple and fast language to describe a Gregorian chant score.
 The project is for now a command-line tool to convert gabc files into real
 score, like for example OpusTeX or GregorioTeX. But it also handles a XML
 format: GregorioXML. You can use the tool to read or write gabc and
 GregorioXML, and to write OpusTeX and GregorioTeX.