man : soelim(1)
soelim - interpret .so requests in groff input
soelim [ -Cv ] [ -Idir ] [ files... ]
soelim reads files and replaces lines of the form
by the contents of file. It is useful if files included
with so need to be preprocessed. Normally, soelim should
be invoked with the -s option of groff.
-C Recognize .so even when followed by a character
other than space or newline.
-Idir This option may be used to specify a directory to
search for files (both those on the command line
and those named in .so lines). The current direc-
tory is always searched first. This option may be
specified more than once, the directories will be
searched in the order specified. No directory
search is performed for files specified using an
-v Print the version number.
Groff Version 1.15 9 April 2000 1