Numeric notation in the SV and related works.

[subrahmanya palurmallampalli]

The following is what I remember from a conversation with my vedic
teacher in India a while ago:

Rg, Yajur and Atharva uses three svaras : udatta, anudatta and svarita
denoted as ',  _  and ". The Saama uses 5 svaras which is why it can be
sung and hence the term saamagaanam. The minimum number of svaras that 
constitute a raagaa is 5.

It also uses numerals to indicate the length of time over which a
given syllable is to be chanted. If the time taken to chant
one syllable is say 1 sec, a 2 at the end of the syllable would indicate
that the syllable is to be chanted for 2 seconds and so on.
A small example of this can be
found at the very end of one of the chapters of the Taittiriiya
upanishad (aananda valli - I think), though it is in the taittiriiya
aaranyakaa.

I am really not competent to say any of the above with authority as
I am not familiar with it.

Hope I am not misleading anybody! 

Subrahmanyam Mallampalli