Basics
launched.
sh -c
Schedule
Run at this interval (seconds)
Cron syntax: 0-59, 0,30, */5
Cron: 0-23, 0,12, */3, etc.
Cron: 1-31, 1,15, */3, etc.
Cron: 1-12, 1,7, */3, etc.
Cron: 0-6, 0,3, etc.

If no schedule is defined, launchd will keep the program running at all times.

Runtime
Run as this user
and/or this group
Run in this working directory
Run with chroot in this directory
Log standard out to this path
Log standard error to this path
Note updating a plist creates a new one with a different UUID.