Selecting Papersize

[Damian McGuckin]

When using the -dpaper=a4 option to 'groff' (which is passed to 'gtroff'), 
the manual says to use '-P-pa4' also (which is passed to the backend).

Does 'gtroff' not pass enough papersize information down its pipeline to 
the backend to make that '-P-pa4' redundant?

Thanks - Damian