Yes those are the baud limits, per Part 97.305
There is a recent attempt to remove that part however:
http://www.arrl.org/news/arrl-executive-committee-okays-filing-symbol-rate-r....
---- Quote --- A question...is it really limited in bandwidth to 19.6K on 2m and 56K on 440 or is it just that this is the maximum used by the modes in common use?