1. A method of indexing digitised entities (E) in a data collection ( 510 ) comprising: inputting basic information (ID n, &lcub;K&rcub;, L) pertaining to at least one distinctive feature (&lcub;K&rcub;) and at least one locator (L) for each digitised entity (E) in a set of entities from the data collection ( 510 ), generating searchable index information (I E ) related to the digitised entities (E) in the set on basis of the basic information (ID n, &lcub;K&rcub;, L), and storing the index information (I E ) in an index database ( 530 ), characterised by generating the index information (I E ) for a particular digitised entity (E: ID n ) on basis of at least one rank parameter (&Dgr;(k 3 ), &Dgr;(k 5 ); &Dgr;(k 19 )) derived from the basic information (ID n, &lcub;K&rcub;, L), the at least one rank parameter (&Dgr;(k 3 ), &Dgr;(k 5 ); &Dgr;(k 19 )) being indicative of a degree of relevance for at least one distinctive feature (k 3, k 5 ; k 19 ) with respect to the digitised entity (E: ID n ).