What does rds in user guide for jbl on time stand for?

I was wondering the same thing and found this answer:

The integrated FM/AM radio tuner is RDS-enabled, which means it can pick up metadata transmitted by some radio stations. A feature called TimeCrawler takes special advantage of this by seeking out stations that broadcast the time of day; it sets the clock automatically to that time.

Source: http://www.pcmag.com/article2/0,2817,1972812,00.asp