Must my pidfile be located in /var/run?

I'm asking in both contexts: technically and stylistically. Can my application/daemon keep a pidfile in `/opt/my_app/run/`? Is it very bad to do so? My need is this: my daemon runs under a specific user, and the implementor must mkdir a new directory in `/var/run`, chown, and chgrp it to make my daemon run. Seems easier to just keep the pidfile local (to the daemon).