The notation system for Carnatic Music is fairly well standardized in Tamil and is unambiguous. It is based on the fact that the syllables 'sa ri ga..' etc. are also sung as 'solfa' and are not mere symbols as in Western Music (C,D,E etc.). See an example of the notation system with explanations. The system is explained with Tamil notation and a transliterated picture in English is also made available

However, the currently used notation in English is not standardised at all. It uses 'S, R, G..' etc. for the notes thereby ignoring the fact that 'sa ri ga..' is both notation and 'solfa'. Many different systems are used in print and internet. In some a capital letter like 'R' means a double note Ri. In others it could mean Chatusruthi Rishabham and 'r' could be Suddha Rishabham. Another system may use all capital letters and use ',' or ';' to prolong the note. In many notations on the web there is no indication about the octave to which the note belongs as it is difficult show dots over or below the characters in ordinary typing on the computer. Consequently I have not given a sample in English.

Gaayaka notation used in Rasika (Windows) software is not only unambiguous but also is entirely based on ordinary text characters and is easy to process either to generate music or to convert to other formats. An explanation of both the format of Gaayaka files and the notation systems are available here