The need for a simple encoding scheme that used only keys available on an ordinary keyboard was felt in the early days of the rec.music.indian.misc (RMIM) Usenet newsgroup where lyrics and trivia about Indian popular movie songs were being discussed.
In parallel was a Sanskrit Mailing list that quickly felt the need of an exact and unambiguous encoding.
ITRANS was in use for the encoding of Indian etexts - it is wider in scope than the Harvard-Kyoto scheme for Devanagari transliteration, with which it coincides largely, but not entirely.
Like the Harvard-Kyoto scheme, the ITRANS romanization only uses diacritical signs found on the common English-language computer keyboard, and it is quite easy to read and pick up.
Specifically, the support for Dravidian short-vowels 'e' and 'o' is considered ambiguous (since Indo-Aryan phonology does not differentiate them from long-vowels 'E' and 'O').