This statement is a Teradata extension to the ANSI SQL:2011 standard.
Unlike the ANSI SQL:2011 requirement, you must create a one-dimensional ARRAY or VARRAY type before you can use it. This variance from the ANSI SQL:2011 standard is compatible with Oracle one-dimensional VARRAY types and with IBM SQL PL one-dimensional ARRAY types.
ANSI SQL:2011 does not define a standard for multidimensional ARRAY types, nor do other major relational database management system vendors support them.