Comet parameter: variable_mod01

Example:
variable_mod01 = 15.9949 M 0 3 -1 0 0
variable_mod01 = 79.966331 STY 0 3 -1 0 0     ... possible phosphorylation on any S, T, Y residue
variable_mod01 = 79.966331 STY 0 3 -1 0 1     ... force peptide IDs to contain at least one phosphorylation mod
variable_mod01 = 42.010565 nK 0 3 -1 0 0     ... acetylation mod to lysine and N-terminus of all peptides
variable_mod01 = 15.994915 n 0 3 0 0 0     ... oxidation of protein's N-terminus
variable_mod01 = 28.0 c 0 3 8 1 0     ... modification applied to C-terminus as lon as the C-term residue is one of last 9 residues in protein
variable_mod01 = -17.026549 Q 0 1 0 2     ... cyclization of N-terminal glutamine to form pyroglutamic acid (elimination of NH3)
variable_mod01 = -18.010565 E 0 1 0 2     ... cyclization of N-terminal glutamic acid to form pyroglutamic acid (elimination of H2O)