GeneralizedTime can be pretty inconvenient when all you want to store is a date (for a birthday, etc.) or only a time.
Yupp!
There doesn't appear to be any standardized syntax just for these purposes.
E.g., if all you want is for your calendar to remind you of someone's birthday, you just need it to tell you on that given day. Your calendar program might put up an alert at 00:01 local time on that date. But "00:01 local time" is a floating time, while GeneralizedTime requires a specific time zone...
http://en.wikipedia.org/wiki/ISO_8601#Calendar_dates
Ciao, Michael.