Recognize .so even when followed by a character other than space or newline.
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 directory 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 absolute path.
Do not add .lf requests (for general use, with non-groff files).
Dont emit .lf requests but TeX comment lines (starting with %) giving the current file and line number.