Gene maps and location databases.

A location database is defined in linear space by a vector of genetic and physical locations for each locus, which may be ordered by virtual sorting on composite location. This contrasts with an interval database defined in metric space, for which location must be inferred by list-processing from numbered intervals which are assigned different ordinals in different tables and overlap other intervals in many ways. A location database has been used for all well-studied experimental organisms. Principles for a human genome database may be derived from this experience.