[firebird-support] How to extract DDL event items involved in a DDL trigger (FB 3.0) from system tables?

[rjm]

For my tool, I like to determine which DDL event items are involved in a DDL 
trigger (FB 3.0).

 

 I already figured out that 
 SELECT IIF(BIN_AND(t.rdb$trigger_type + 1, 0) = 0, 'BEFORE', 'AFTER') AS 
TriggerMoment FROM rdb$triggers
 will give me the BEFORE or AFTER moment.
 

 But how can I query from rdb$triggers (rdb$trigger_type field) whether 'CREATE 
TABLE' or 'ALTER CHARACTER SET' or any other DDL event is involved?
 

 Thanks,
 Robert