+ If "isRoot" is omitted or specified as false, then any given row
+ in the table may exist only when there is at least one reference
+ to it, with refType "strong", from a different row (in the same
+ table or a different table). This is a "deferred" action:
+ unreferenced rows in the table are deleted just before transaction
+ commit. If "isRoot" is specified as true, then rows in the table
+ exist independent of any references (they can be thought of as
+ part of the "root set" in a garbage collector).
+
+ For compatibility with schemas created before "isRoot" was
+ introduced, if "isRoot" is omitted or false in every
+ <table-schema> in a given <database-schema>, then every table is
+ part of the root set.
+