Claims for Topic Maps interoperability have been standing so far on formal representation of subjects by topics, and identification of topics by controlled vocabularies or Published Subjects. Those features allow topics to be merged on the basis of common identifiers, leading to aggregation of relevant information or knowledge expressed by characteristics of the merged topics.

But what should happen to associations at merging time remains an open issue in many cases. According to current standard processing requirements, only exactly identical associations will be merged. Default standard definition of association templates, there is so far no standard rules for discovering and dealing with associations having similar patterns of roles, or representing the same association type with slightly different patterns. And default proper association merging rules, Topic Maps are at risk to be cluttered up with redundant or non-consistent associations, after several successive merging.