The C-Score measures the level of characterization of a proteoform in relation to the others in the database. This score, described in LeDuc et al.1), uses a Bayesian approach that assigns a likelihood to each candidate proteoform based on the observed MS data.

A C-Score of 3 indicates that there are two proteoforms in the database that equally explain the observed data. A score of 40 or higher is considered strong evidence of a unique characterization.