Index: trunk/psphot/src/psphotSourceSize.c
===================================================================
--- trunk/psphot/src/psphotSourceSize.c	(revision 17112)
+++ trunk/psphot/src/psphotSourceSize.c	(revision 17113)
@@ -3,6 +3,8 @@
 
 // we need to call this function after sources have been fitted to the PSF model and
-// subtracted.  this function examines the 9 pixels in the 3x3 square containing the peak and
-// compares the observed flux to the model.
+// subtracted.  To determine the CR-nature, this function examines the 9 pixels in the 3x3
+// square containing the peak and compares the observed flux to the model.  To determine
+// the EXT-nature, this function measures the amount of positive or negative total
+// deviation from the psf model at the r = FWHM/2 position
 
 bool psphotSourceSize (pmReadout *readout, psArray *sources, psMetadata *recipe, long first) {