The most common supposition has been that these two signs are case suffixes, JAR for the genitive and ARROW for the locative or the dative. However, most (though not all) sequences preceding these two signs are mutually exclusive, thus making it improbable that they are case-markers (which are generally recognized from the circumstance that they are added to the same nouns but in different contexts). These two signs are also found to be more closely attached to their respective preceding signs than would be the case if they were case-markers (e.g. FISH and ARROW pair).
Further, case-endings in the oldest Tamil inscriptions do not occur text-finally (except in very few instances influenced by Prakrit). Thus it appears likely that these two signs are grammatical morphs, but not case suffixes. This leaves only the possibility that they represent gender, or rather person-number-gender, since single suffixes can serve as combined person-number-gender markers in Dravidian.
The most common word for the arrow in the Dravidian languages is ampu (Ta., Ma.) or ambu (Ka., Te.), which can be reconstructed as *ampu in Proto-Dravidian (DEDR 178). Since the ARROW sign is known to function as a grammatical suffix, the phonetic value ampu also stands for the non-masculine singular suffix. This grammatical morph can also be reconstructed as *-(a)mp(u) in Proto-Dravidian as it occurs widely in South, South-Central and Central Dravidian Languages:
Old Telugu : -(a)mbu/-(a)bu>(a)mmu-(a)mu
Old Kannada : -(a)m>-(a)mu/-(a)vu
Tamil : -(a)m.
In Old Telugu, there was only a two-way grammatical distinction for gender, known as mahat and a-mahat. The feminine was included in the a-mahat category in the singular, and in the mahat category in the plural (K.M. Sastri: ibid.):
|mahat||male||males & females|
Correspondingly the gender suffixes in Old Telugu were as follows:
Masculine Singular : -(a)nru> -(a)nru, -(a)ndu
Non-Masculine Singular* : -(a)mbu/-(a)bu>-(a)mmu, -(a)mu
(* K.M. Sastri refers to this category as 'neuter'. However as females are also included in the singular, it is better described as 'non-masculine'.) >