I have just made some simple TeX validator and parser.

To make it any useful I need a list of all TeX constructs we support. Everything that contains some other function will be considered illegal.

Here is short list of obvious ones (classified by arity):

0 alpha beta gamma theta tau vartheta 0 pi upsilon varpi phi delta kappa 0 rho varphi epsilon lambda varrho chi 0 varepsilon mu sigma psi zeta nu 0 varsigma omega eta 0 Gamma Lambda Sigma Psi Delta Upsilon Omega Theta Pi Phi 1 sqrt 2 frac

Do you have some more complete list ? Parser should have no problem with a couple thousands, so don't hesitate.