systempapername() returns the name of the default paper to be used by a program.
This name is obtained by looking in that order at the
PAPERCONF environment variable, at the contents of the file returned by
systempapersizefile() or by using
defaultpapername() as a last chance.
defaultpapername() returns the name of the default paper to use if it is impossible to get
its name from the environment.
systempapersizefile() returns the path of the papersize file to use.
This path is obtained by looking at the
PAPERCONF environment variable or by calling
defaultpapersizefile returns the path of the default papersize file.