Index: trunk/doc/developer/polybool2/algo.txt
===================================================================
--- trunk/doc/developer/polybool2/algo.txt	(revision 36886)
+++ trunk/doc/developer/polybool2/algo.txt	(revision 36887)
@@ -20,13 +20,18 @@
 	1.4. handle overlaps
 		1.4.1. map curves that are fully overlapping; their endpoints must match
 		1.4.2. take a group of all overlapping curves for a single pair of endpoints
+		       and remove all but one curve
+(		1.4.2. take a group of all overlapping curves for a single pair of endpoints
 			- if there is at least one other curve ends on both endpoints:
 				- if there are even number of curves in the group, remove all curves
 				- otherwise remove all curves from this group except one
 			- else this is a stub: remove all curves of this group
+)
 
 2. split: list clean regions:
 	2.1. map all possible regions
+	     Note: overlapping lines, e.g. in a bone, O--O, case may result in
+	     having a curve that's not part of any region; ignore such curves
 	2.2. for each region starting frome ach intersection (curve-endpoint)
 	     check each curve that's not part of the region permiter; if that
 	     curve goes into the region, discard the region (as it is non-clean)