The scheme used for the transliteration of Tamil songs in English in this site may differ from other schemes. Basically, I have followed a scheme that is most convenient for reading and which has saved me a lot of time in typing the songs.
The advantage of this scheme is readability. The disadvantage, of course, is inability to distinguish between the n's and l's. But, most occasions reveal the correct interpretation, thanks to context. Just like the thamizh language itself.
That brings up an interesting point: Is it 'padagu' or 'bataku'? Great question! Well, to the learned, it is 'padagu', because, there is no such word as 'bataku'. Does that mean you have to know the language to speak it? Yes. Is it not true with any language, say, English?
Here's the scheme:
|a, aa, i, ee, u, oo, e, ae, ai, o, oa, au|
|Vallinam:||k (g), ch (s, j), t (d), th (dh), p (b), r|
|Mellinam:||ng, nj, n, n, m, n|
|Idaiyinam:||y, r, l, v, zh, l|
Here are a few examples illustrating the use of consonants: