> Could you please tell me where can I find the list
> of all built-in procedures/functions in FireBird (1.0, 1.02,1.5 beta)
> suitable for use in a stored procedure/trigger ?

As far as I know, there is no "list" anywhere. It can use UDF (User Defined
Functions) inside stored procedures and triggers. Since UDFs are, well,
"User Defined", not "Firebird Developer Defined", there is an ever growing
list, and you can create your own.

Check out http://www.ibphoenix.com/main.nfs?a=ibphoenix&page=ibp_udf_libs
for a list of some of the already existing UDF libraries, many with source
code that you can modify or learn from and expand on.