Is the 'Belongs To' symbol, with two dots below it, a valid symbol for 'Such That' ?

Question

Here's 'Belongs To', for reference: http://www.scenta.co.uk/tcaep/images/belongst.gif

Answer 1

The backwards epsilon is a standard notation. I believe that is usually best to write the words. I use st quite often, however it is not standard.

Answer 2

I have seen a "such that" symbol that is a backwards "element of" (I am assuming that is the same as "belongs to").

However, I must say I am not a fan of a symbol for "such that" within proofs or statements of theorems as I believe it only serves to obfuscate.