Index: intersect.h
===================================================================
--- intersect.h	(revision 2240)
+++ intersect.h	(revision 2241)
@@ -27,5 +27,10 @@
 #include <libcschem/concrete.h>
 
 /* Return number of intersections between o1 and o2; optionally loads iscp
-   with intersection points, up to iscp_len */
+   with intersection points, up to iscp_len. If iscp is NULL, precise
+   intersection caclulation is done usign thickness of objects and the number
+   of different object-object intersections is returned. If iscp is not NULL,
+   only centerline-intersections are considered and iscp coords are all on
+   object centerlines (number of total centerline iscs returned, may be
+   larger than iscp_len) */
 long csch_obj_intersect_obj(csch_sheet_t *sheet, csch_chdr_t *o1, csch_chdr_t *o2, g2d_vect_t *iscp, long iscp_len);