Which is the correct sintax to create external udf into fdb?

if I have a function p_round into a pudf.dll library under UDF firebird
installation directory

sqlanywhere tell me to execute:
create FUNCTION pround(
in ntc DOUBLE PRECISION, in ntr INTEGER)
RETURNS DOUBLE PRECISION
external name 'p_round@...';

ibexpert
DECLARE EXTERNAL FUNCTION pround
DOUBLE PRECISION, INTEGER
RETURNS DOUBLE PRECISION BY VALUE
ENTRY_POINT 'pudf_p_round' MODULE_NAME 'pudf';


where can I find correct sintax?


Codebue Fabio