Abstract: A data structure is described which enables at least one behavioural characteristic of a first entity to be determined by providing at least one semantic information element as meta-data which describes a characteristic of a discernable feature of the first entity using an interpretable compiler. This semantic meta-data can be compared to meta-data providing semantic information describing a characteristic of a discernable feature of at least one other entity. Meta-data may be passed dynamically with messages exchange by ORBs, or alternatively, it may be stored. In either case, a compatibility statement can be generated which collates the semantic information elements of the first entity with the semantic information elements of the at least one other entity.