.SH "TABLE RELATIONSHIPS"
.PP
The following diagram shows the relationship among tables in the
-database. Each node represents a table. Each edge leads from the
+database. Each node represents a table. Tables that are part of the
+``root set'' are shown with double borders. Each edge leads from the
table that contains it and points to the table that its value
-represents. Edges are labeled with their column names.
+represents. Edges are labeled with their column names. Thick lines
+represent strong references; thin lines represent weak references.
.RS -1in
"""
erStream = open(erFile, "r")