SQL has a create table statement. This will need to be extended to
allow specification of time-varying relations in addition to
conventional relations. Other meta-data, such as the nature of
interpolation to be imposed on continuous data represented discretely,
must be included in the schema. Also, the schema of a relation may need to be
changed to indicate a conversion from a time-varying relation, or vice
versa. This will probably be a particularly easy extension to design.