In the soap-calendar.txt document, it says:
// <s d="YYYYMMDD['T'HHMMSS[Z]]" [tz="timezone_identifier"]>
// tz="java timezone identifier" (see list at bottom of this file!)
(At the bottom of the file)
Each iCalendar object can define custom time zone names. For our own web
client, there is a list of well-known time zones. These are stored in
LDAP. See conf/ldap/zimbra.ldif for their definition. The time zone ID
is the cn attribute.

I found the zimbra.ldif file, but I did not find any time zone IDs.

Is it possible that our zimbra.ldif file does not contain the time zones because we have not configured these?
If so, how do the time zones get configured?