deroff \- remove nroff, troff, tbl and eqn constructs
reads each file in sequence
command lines, backslash constructions, macro definitions,
(between `.EQ' and `.EN' lines or between
and writes the remainder on the standard output.
follows chains of included files
(`.so' and `.nx' commands);
if a file has already been included, a `.so' is ignored and a `.nx' terminates execution.
If no input file is given,
reads from the standard input file.
flag is given, the output is a word list, one `word' (string of letters, digits, and apostrophes,
beginning with a letter; apostrophes are removed) per line, and all other characters ignored.
Otherwise, the output follows the original, with the deletions mentioned above.
so it can be confused by subtle constructs.
Most errors result in too much rather than too little output.