The "include" statement can be used to include the contents of one file
inside another.
include "filename"
If the filename cannot be found as is, and it is not an absolute path, and if the environment variable MUPPATH is set, Mup will search for the file in each directory listed in MUPPATH. On Unix systems, the directories are separated by colons. On systems with DOS-like file naming conventions, they are separated by semicolons. This may be useful, for example, if you have a number of "boilerplate" files that you want to include in lots of songs. You can put them in some directory and set MUPPATH to list that directory, then any Mup files you have can refer to them.