What is a *.CKP file?

[Ken Turkowski]

In my /usr/lib/crontab, there is a line of the form:

40 4 * * * find / '(' -name '#*' -o -name '*.CKP' ')' -a -atime +3 -a -exec rm -f {} ';'

Recent discussion on USENET revealed the purpose (or at least the destiny)
of the #* files.  But what are the *.CKP files used for?  And what does CKP
stand for?
-- 

Ken Turkowski @ CADLINC, Menlo Park, CA
UUCP: {amd,decwrl,hplabs,nsc,seismo,spar}!turtlevax!ken
ARPA: turtlevax!ken at DECWRL.ARPA