The general layout of the printed scores may be changed in many ways.

For example, when running the program, one or more format files may be specified as program arguments using the command line option -F (see the file options.txt).
A format file contains a sequence of lines where empty and lines beginning with a '%' are ignored.
Each line contains a pair consisting of the parameter name (without the "%%") and the associated value(s).

Alternatively one or more format parameters may be specified directly as run time argument pairs using the following syntax.
The first argument is the format parameter name preceded by two dashes (eg. --vocalfont) and the second argument is the new value.
If the value contains spaces, it should be enclosed by quotes when the program is run from a shell. For example, the following command will run abcm2ps on the file myfile.abc changing the format parameter vocalfont to 'Arial 13':

	abcm2ps --vocalfont 'Arial 13' myfile.abc

Format parameters may be specified inside an ABC tune in one of two ways. Pseudo-comments are specified by beginning a line with '%%'. The syntax is simply:

	%%parameter_name new_value

Alternatively, a parameter change may be indicated inside the body of the tune using the I: information field. For example:
	CDEF | [I:annotationfont Arial 13] "^bla" GABc |
The keyword "lock" may appear at the end of a parameter value. After such a keyword has been found, the parameter will not be changed anymore unless "lock" appears again.
It is implicitly appended in the command line arguments so that these parameters take precedence and override any other changes.
	abcm2ps --vocalfont 'Arial 13' myfile.abc
in myfile.abc:
	%%vocalfont Times-Roman *		% <- ignored
	%%vocalfont Helvetica * lock		% <- vocalfont = 'Helvetica 13'