In all conforming TM Applications, two assertions are merged to become a single assertion when their respective a-nodes are deemed to represent the same subject. All TM Applications are required to define merging rules that apply uniformly to all assertions, such that they will always be merged during the process of converting a well-formed topic map graph into a fully merged topic map graph under the conditions described in the following subclauses, and such that they will be automatically merged under no other conditions and on no other basis: