seeming repetition in info manual

[Dave Kemper]

Certainly not a showstopper of any sort, but one oddity:
doc/groff.texi documents the .sp request by saying "Space downward by
@var{distance}.  With no argument, the drawing position is advanced
downward by one vee."  This is followed by four other sentences, and
then "If @var{distance} is not specified, @samp{1v} is assumed," which
seems to only re-word the earlier sentence.  Are they saying something
subtly different, or is one of them redundant?