ALTER TABLE DROP COLUMN rollback leaves column – what is the documented behavior in Firebird 4.0?

Goal

To determine whether a transaction that performs ALTER TABLE DROP COLUMN can be fully rolled back in Firebird 4.0, restoring the original schema state without leaving residual objects.

Unresolved behavior

Firebird 2.5+ supports transactional DDL, but documentation notes that dropping a column is not fully reversible. The behavior appears to vary between releases (2.5, 3.0, 4.0). No explicit statement confirms that a rollback will always remove the dropped column in 4.0.

Specific questions

• Does a ROLLBACK after ALTER TABLE DROP COLUMN in Firebird 4.0 always revert the schema to its pre‑change state?
• What, if any, additional cleanup steps are required to fully restore the dropped column when a rollback fails to remove it?
• How does Firebird’s release‑notes documentation describe this rollback scenario, and are there version‑specific notes for 4.0?