You may use parenthesis, '(' and ')', and some common abbreviations (Me, Et, Pr, Bu, Ad, Ph, Bn, Tr, Ac, Bz, Piv, Ms, Ts, Tf, Boc, Cbz ). Some characters are ignored to facilitate cut & paste.
The formula in Hill notation, the molecular mass and the elemental composition are returned. There is no syntax checking - so Garbage In → Garbage Out.
For a comprehensive list of abbreviations of protecting groups see
"Protective groups in organic sythesis", Greene, T.W. and Wuts, P.G.M., J. Wiley
& Sons (1991), New York,
"Rules for abbreviation of protecting groups",
Brimble, M.A; StC. Black, D.; Hartshorn, R.; Rauter, A.P.;
Sha, C.-K.; Sydnes, L.K.; Pure Appl. Chem. 85 (2013) 307-313.