Changing vertical spacing in ditroff with -me macros

[James Pinakis]

Does anyone have any idea on how to change the vertical spacing
in ditroff when using the -me macro library?  What I really
want to do is have pointsize 12 and vertical spacing 22.

I have managed to change the pointsize with
	.nr pp 12 
	.nr sp 12

I realise that the vertical spacing is defined to be proportional
to the pointsize and that the proportion is saved in number registers
($R and (Rr, but when I change these registers it makes no difference.

Do these registers need to be set at the start of every section,
paragraph or chapter or is there some other way of doing it?

Thanks in advance,

James.
jamesp at wacsvax.uwa.oz
"...Whatever you do, just don't be a WYSIWYG..." - Yul Brennar.