Dmitry,

D> Can you think of a case when a constraint could be violated as a result of a
D> cast operation? I.e. when CAST (<value> as <domain>) could be different than
D> CAST (<value> as TYPE OF <domain>)?

create domain somedomain as integer check (value in (1, 2, 3));

select cast (4 as somedomain)
from RDB$DATABASE

Ciao
--
Nando Dessena