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.