Index: branches/eam_branches/relphot.20210521/src/relphot.c
===================================================================
--- branches/eam_branches/relphot.20210521/src/relphot.c	(revision 41602)
+++ branches/eam_branches/relphot.20210521/src/relphot.c	(revision 41604)
@@ -34,5 +34,7 @@
   switch (mode) {
     case UPDATE_IMAGES:
+      // calculate zero points for images (may group my exposure [mosaic], night [tgroups]; may measure flat-correction)
       // IF CALLED WITH NLOOP == 0, DOES NOT LOAD bcatalog, just loads image table and generates ImageSubset.dat
+      // If called with -update, calls reload_catalogs() just like apply_offsets
       relphot_images (skylist);
       relphot_free (sky, skylist);
@@ -52,5 +54,6 @@
 
     case PARALLEL_REGIONS:
-      // run image updates in parallel across multiple remote machines
+      // calculate zero points for images (may group my exposure [mosaic], night [tgroups]; may measure flat-correction)
+      // equivalent to relphot_images, but run in parallel across multiple remote machines
       relphot_parallel_regions (sky);
       relphot_free (sky, skylist);