[tz] Question about the UNTIL fields

Hello everyone, I'm working on a TZDB parser for a PHP project and reading the zic8.txt I came across with the following information: The month, day, and time of day have the same format as the IN, ON, and AT

fields of a rule

However, I could not find any Zone line in the latest version of the TZDB containing relative dates, such as "lastSun" or "sun>=5", but only absolute dates. Is this a mistake in the documentation or are relative dates actually supported on those lines but have never been used? - Marcos