[Dovecot] Sieve vacation variables reference

Hi There.

We are using dovecot v2.2.4 with pigeonhole 0.4.1 (both compiled from source) Centos 6.4.

Sorry for the dumb question in advance if I'm just missing an obvious link somewhere (also if I've got the terminology all wrong!), but could someone point me to the reference list for "vacation", e.g.:

vacation :days :subject :addresses :from

is there a definitive list of things like "days", "subject" etc?

Thanks

Simon