[Buddha-l] Sanskrit vs Middle Indic

[chong go sunim]

Can anyone help me with the proper way to describe the language of the dharanis and mantras that appear in many of the Chinese sutras? Can these be described as being transliterated from the Sanskrit orginal? Or are they actually some form of Middle Indic, that would be improper to describe as Sanskrit?
 
This issue came up while working with the "Great Compassion Dharani" from the "Thousand Hands Sutra". Early printed Korean editions(1476 C.E.) even have what looks like Sanskrit annotations next to the Chinese characters.
Thanks!
 
with plams together,
Chong Go