There can be at most 256 text strings, but it's worth noting that a) some of the earlier numbers (I think maybe 17-65 or so?) shouldn't be used because they'd conflict with animations, and b) TSF doesn't seem to support text strings above 16 at all. Also you can totally have a text string more than 512 characters: if you fill one all the way up, JJ2 will continue reading the next one until it hits a blank byte.