This schema defines the 'tabular catalog metadocument' that is used to describe tabular catalog. 'Catalog' here is used in the database sense, as a collection of tables - they need not be sky catalogs. The schema is self-contained, and might be referred to from other schemas. Element names are similar where possible to the VO-standard metadata documents. In a document that informs an AstroGrid skycatserver installation, the root element must be DatasetDescription in this namespace. Other documents may use Catalog or Table as root elements, but these documents will not be usuable in AstroGrid software. This version of the schema is a placeholder release to synchronise with the current state of the AstroGrid DSA codebase; it will be the basis of a future release that deals more explicitly with the issue of epoch etc. Describes a collection of catalogues presumed to be held in the same database; the catalogues need not be logically connected but must be accessible through the same interfaces, such a common JDBC connection. This must be the root element in a document that informs an AstroGrid skycatserver installation. Allowed types of table columns. The UCD version describes which version of the UCD dictionary to use, eg '1' or '1+'