As a guess the problem with .DS 1 seems to be that the text is written with .i = 0 into a diversion with .l from before .DS, then the diversion is output in .nf mode with .i > 0 ... Of course then the right margin is shifted. So for .DS 1 .l in the diversion should be reduced by \n(Siu (m.tmac line 2086).
--Carsten
