What file holds the values for "Show As" (i.e. Busy, Free, etc), as I wish to customize these and maybe even make additional values.

And how would I go about adding/removing a string based on a specific value selection? For example, If I create a value named CANCELLED, and I assign that Show As state to an appointment, I want it to insert "(Cancelled)" into the title of the appointment for me.

EDIT: Zimbra Collaboration Suite (Open Source)