1 Source with TS>35, which went to TS<25 when changing the diffuse model (Section 3.7.3) or the analysis method (Section 3.7.4). Sources with TS<=35 are not flagged with this bit because normal statistical fluctuations can push them to TS<25.
 2 Not used.
 3 Flux (>1GeV) or energy flux (>100MeV) changed by more than 3{sigma} when changing the diffuse model or the analysis method. Requires also that the flux change by more than 35% (to not flag strong sources).
 4 Source-to-background ratio less than 10% in highest band in which TS>25 Background is integrated over {pi}r_68_^2^ or 1 square degree, whichever is smaller.
 5 Closer than {theta}_ref_ from a brighter neighbor. {theta}_ref_ is defined in the highest band in which source TS>25, or the band with highest TS if all are <25. {theta}_ref_ is set to 2.17{deg} (FWHM) below 300MeV, 1.38{deg} between 300MeV and 1GeV, 0.87{deg} between 1 and 3GeV, 0.67{deg} between 3 and 10GeV, and 0.45{deg} above 10GeV (2r_68_).
 6 On top of an interstellar gas clump or small-scale defect in the model of diffuse emission; equivalent to the c designator in the source name (Section 3.8).
 7 Unstable position determination; result from gtfindsrc outside the 95% ellipse from pointlike.
 8 Not used.
 9 Localization Quality >8 in pointlike (Section 3.1) or long axis of 95% ellipse >0.25{deg}.
10 Spectral Fit Quality >16.3 (Equation (3) of Nolan et al. 2012 (J/ApJS/199/31); 2FGL).
11 Possibly due to the Sun (Section 3.6).
12 Highly curved spectrum; LogParabola {beta} fixed to 1 or PLExpCutoff Spectral_Index fixed to 0.5 (see Section 3.3).