An assertion is a subgraph of a topic map graph that consists of certain arcs and the nodes that serve as their endpoints, constructed in conformance to the rules set forth in this clause. Every node, regardless of its node type, is eligible to be a role player (i.e., to serve as the x endpoint of a Cx arc) in any number of assertions. Every arc is a component of a single assertion. The entire significance of every arc is its service as a unique component of a single assertion.

see Rules for Assertions