SABLE defines following tags:
mark - allows engine to report to calling app when it reaches given mark
emph - emphasis of contained text
break - prosodic break
pitch - number, percentage or enumeration
rate - number, percentage or enumeration
volume - number, percentage or enumeration
audio - audio sample played in parallel or in sequence
engine - substitute data for contents if using given engine
pron - phonetic replacement for contained string
sayas - dates, times, phone numbers, currency etc.
language - ISO639 language code
speaker - select voice font by name, age and gender
div - sentence or paragraph