| A data type is a set of representable values. Every representable value belongs to at least one data type and some belong to several data types. [...] |
| A constructed type is specified using one of SQL's data type constructors, ARRAY , MULTISET , REF , and ROW . A constructed type is either an array type, a multiset type, a reference type, or a row type, according to whether it is specified with ARRAY , MULTISET , REF , or ROW , respectively. Array types and multiset types are known generically as collection types. |
