Pre-defined Collection table in Oracle

select owner, type_name, coll_type, elem_type_name, length from dba_coll_types
where TYPE_NAME IN ('DBMS_DEBUG_VC2COLL', 'KU$_VCNT');

SELECT COLUMN_VALUE FROM TABLE(SYS.DBMS_DEBUG_VC2COLL('123', 'ABCD', 'LMN'));

SELECT COLUMN_VALUE FROM TABLE(SYS.KU$_VCNT('123', 'ABCD', 'LMN'));

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http://awads.net/wp/2005/10/13/pre-defined-collection-types-in-oracle