/var/spool is traditionally used for machine-local data being spooled to or from UNIX subsystems. For example, print jobs are spooled here for delivery to the lineprinter daemon, out-bound mail is spooled for delivery to remote systems, and UUCP files are spooled for transmission to UUCP neighbors. In-bound mail and news are spooled here for delivery to users, and at and cron jobs are spooled for delayed execution by the cron daemon.
UUCP lock files should be placed in /var/lock. See the above section on /var/lock.