This is a pseudo table that has been designed to track subtables. It enables you to map partitions of tables to catalog ids and subtables to parent tables.

The content of LOCALSUBTABLES has the same columns as LOCALTABLEATOMS with the addition of partition id and parent table object id but it only displays subtables.

LOCALTABLEATOMS still only returns supertables.

PlatformSchema will return subtables and the LOCALTABLEATOMS and LOCALSUBTABLES pseudo tables filter out only the results that they need.