Minimum unique abbreviation of option is acceptable. You may use double hyphens instead of single hyphen to denote options. You may use white space in place of the equals sign to separate an option name from its value.
This program is part of Netpbm.
pnmcomp was obsoleted by pamcomp, introduced with Netpbm 10.21 (March 2004). pamcomp is backward compatible with pnmcomp, plus adds many additional functions, including the ability to process PAM images, and tends to produce better transparency results.
pnmcomp remains in the Netpbm package because it may have fewer bugs for now than pamcomp, and is in some environments faster (but newer compilers have been seen to produce code for pamcomp significantly faster than that for pnmcomp). Some day, pnmcomp will probably become an alias for pamcomp.
You can use the pamcomp documentation for pnmcomp, considering the following differences: