The problem of identity and reference is receiving increasing attention in the (semantic) web community and is emerging as one of the key features which distinguish traditional knowledge representation from knowledge representation on the web with respect to data interlinking and knowledge integration on a large scale. As part of this debate, the OKKAM project proposed the creation of an Entity Name System which provides rigid identifiers, named OKKAMids, for any type of concrete and particular entities, and links OKKAMids to existing identifiers which have