Using ontologies allows agents to put meaning behind the terms appearing in the information exchanges. Supporting us on this fact, we propose an entity named focus allowing to represent various kinds of information contents : documents, data bases, services, agents' capabilities, etc. A focus consists of a weighting of the concepts of an ontology in order to indicate which meanings are important for the agent which has set it up. To help the capture of the values in the focus we present a procedure to spread the weightings in the focus. Then we define a measure of relevance of a focus compared to another. The originality of our approach lies in the fact that the focus is an exchangeable entity between the agents and does not require a centralization of the data collections.