Index: 06_hierarchy.html
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--- 06_hierarchy.html	(revision 4732)
+++ 06_hierarchy.html	(revision 4733)
@@ -164,6 +164,15 @@
 orthogonal to the symbol library paths (but upon the user's decision there
 might be overlap between the two).
 
+<p>{des6:29}
+An implementatin that supports project files typically keeps a list of all
+root sheets in the project file and another (auxiliary, aux) list of all
+other referenced from the root sheets. When a new reference is made (new
+symbol is placed with cschem/child/* attribute), the aux list of the project
+file is extended with the new file. Thus the project file always contains a
+full list of sheet files needed for reproducing the hierarchy.
+
+
 <h2> 6.3.1. Network connections - network parameters </h2>
 
 <p>{des6:19}