Responding to a query on the date of the Tolkāppiyam, I obtained some pages in the 2nd edition of Early Tamil Epigraphy (ETE) by Iravatham Mahadevan published in 2014. In his first edition Mahadevan had said on p. 231, “It is thus clear that this grammatical work must have been composed after the puḷḷi was invented and had become an integral part of Tamil writing. Judging from the available evidence of the earliest occurrence of the puḷḷi from about the end of the 1st century A.D., Tolkāppiyam was composed most probably not earlier than the Late Tamil-Brāhmī Period (ca. 2nd-4th centuries A.D.)” Unfortunately, Mahadevan had not consulted a crucial article by Rajam Ramamurti of 1982 entitled, "The Relevance of the Term Mey, Oṟṟu, and Puḷḷi To the System of Tamil Morpho-phonemics" in International Journal of Dravidian Linguistics, 11 , no. 1, pp. 167-183. In this article, it is stated:
 
"From what Rule 106 says, we understand that there existed a convention, either earlier or contemporary, of marking an extra short u with a dot. The tone of Rules 15 and 105 in the Tolkāppiyam suggests that the author of the text made his own rule of marking a vowelless consonant with a dot.
 
"It is possible that there existed in the pre-Tolkāppiyam period, the convention of marking an extra short u with a dot and the author of Tolkāppiyam extended the convention to the class of vowelless consonants..." 

In other words, it was Tolkāppiyar, the author of the Tolkāppiyam, who invented the convention of marking a pure consonant with a dot. This means that the Tolkāppiyam must precede any epigraphic occurrence of the dot (puḷḷi) and not after as Mahadevan has stated.  

The crux of the problem seems to be the interpretation of the rule Tolkāppiyam 15. Mahadevan has used Kamil Zvelebil’s outdated 1972 translation, “The nature of the consonant is to be provided with a dot.” Ramamurti (1982:180)’s more precise translation using the imperative/optative interpretation is, "Let/May it be the nature of mey (consonant) to stay with a puḷḷi (dot).” If the use of dots to indicate pure consonants was already present, he would not have used the imperative/optative construction in the rule.

ETE's 2nd edition’s bibliography includes the afore-mentioned article, Ramamurti (1982). (Both editions’ bibliographies also include V. S. Rajam’s  A Reference Grammar of Classical Tamil Poetry, wherein the imperative/optative use of verbal noun is discussed on p. 820.)  But in the discussion on puḷḷi in ETE's 2nd edition, Mahadevan does not discuss Ramamurti (1982) but essentially presents the same date for Tolkāppiyam as in the first edition. See attachment. Mahadevan has not discussed why he still maintained his earlier conclusion.  Has there been any discussion of this issue by anybody else?

Thanks

Regards,
Palaniappan