Thanks for the quick feedback.

When you say that a procedure is NOT a function, you forgot that what
is called "STORED PROCEDURE" in FIREBIRD can actually returns values
like a standard programming language function:

CREATE PROCEDURE procA (inputPar INTEGER)
RETURNS (outputPar INTEGER)
AS BEGIN
...
END

And you call it

EXECUTE PROCEDURE procA(25) RETURNING_VALUES var1;


FIREBIRD would gain flexibility if we could create functions based on
PSQL avoiding the need to rely on non-portable and potentially
dangerous UDF.