This article is from a FAQ concerning SCO operating
systems. While some of the information may be applicable to any OS,
or any Unix or Linux OS, it may be specific to SCO Xenix, Open
There is lots of Linux, Mac OS X and general Unix info elsewhere on
this site: Search this site is the best
way to find anything.
See the man page on your Linux system and compare it to the man
page on your SCO box- they have differing ideas on what the default
for "c" should be. SCO took the path that says you should be able
to read old archives without using a different flag; Linux as usual
decided that new is better.
As it's rather well documented in both cases, I don't think
either of them are "wrong".