Index: 02_data_imp.html
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--- 02_data_imp.html	(revision 4724)
+++ 02_data_imp.html	(revision 4725)
@@ -94,7 +94,9 @@
 debuggers can assist the user to navigate to the source line(s) that contributed
 to a specific instruction or runtime situation, cschem UIs should be able to
 navigate the user to the source(s) in the <i>concrete</i> model that caused
-a specific effect in the <i>abstract</i> model.
+a specific effect in the <i>abstract</i> model. How the source references
+are stored in memory is up to the implementation, but when the model is
+saved/exported (e.g. to disk), it should use UIDs as specified.
 
 <p>{imp2:12}
 A common example is (<i>abstract</i>) networks. The user, looking at a PCB or