[C/N] versus [C+N/Fe] plots for globular clusters 47 TUC, M 71, M 4, and M 5. Light-gray dots are APOGEE halo field stars with similar Mg and Fe abundances to the cluster. Stars outlined in black are members of the respective cluster, where those colored in red are considered peculiar enriched stars within the cluster, while those colored in cyan are those that are not peculiar and are similar to the field stars. The black dashed line represents the cut we did to remove the peculiar stars from the calibration sample. A representative error bar is shown in the bottom-left corner of each panel for each cluster.