[[duilioisola]]

En realidad deberías filtrar por RDB$RELATION_TYPE

Según
FB 2.5
https://www.firebirdsql.org/file/doc...relations.html
FB 5.0
https://firebirdsql.net/file/documen...relations.html

RDB$RELATION_TYPE
SMALLINT
The type of the relation object being described:

0 - system or user-defined table
1 - view
2 - external table
3 - monitoring table
4 - connection-level GTT (PRESERVE ROWS)
5 - transaction-level GTT (DELETE ROWS)