Classical Tibetan refers to the language of any text written in
Tibetic after the
Old Tibetan period and before the modern period, but it particularly refers to the language of early canonical texts translated from other languages, especially
Sanskrit. The
phonology implied by Classical Tibetan
orthography is basically identical to the phonology of Old Tibetan, but the
grammar varies greatly depending on period and geographic origin of the author. Such variation is an under-researched topic.