I have also found that ITRANS is the India Language Transliteration
program. This is also an India-wide application and as such a little
odd in Tamil. The problem seems to be that it is easier physically
to input most Indic languages using an English transliteration
program because of the number of phonemes, think of Punjabi. Who
wants to use the shift or alt key for every second letter?
And yes I did jumble keyboard layout and fonts again. Sorry. In the
first Tamil application I used different keyboard layouts were
chosen under the font menu.