Dear colleagues,

I am interested in determining when, where and in what function Brāhmī-derived scripts first started using a subscript dot in order to distinguish certain phonemes or allophones, such as:

- y vs. ẏ in Bengali: য় vs. য (a clearly related sign, though not a dot, exists in Oriya in the same function)
- r vs. v/b in Bengali: র vs. ব
- ṛ vs. ḍ in Nagari (and Oriya, and probably also in other scripts): ड vs. ड़

Since the same device is used in partly same, partly different functions in different North Indian scripts, one wonders whether there is a single source script and single original function dating back to before the proto-regional scripts became, or whether the use of this diacritic developed in one specific area (whether in a single or in more than one function) and diffused from there to other regions and their scripts.

I haven't been able to find anything about the early history of the use of the dubscript diacritic dot in any of the usual handbooks, and would be grateful for pointers to relevant secondary literature as well as concrete examples from early (1st millennium CE, if possible) manuscripts or inscriptions.

Thanks, and best wishes,

Arlo Griffiths
École française d'Extrême-Orient