When a stored procedure is called by sybase_query() and returns an error value, sybase_query does not return a false value.

I made a stored procedure:
create proc p_err as return -999
go

Then, from php:
echo sybase_query('EXEC p_err')

returns:
(Resource id #2)

Arguably, this could be considered the correct behaviour; but in any case, there should be a way of getting at the return value (perhaps a function sybase_status() which returns the value of the last sybase_query()?). Looking through the source code, the status return is simply discarded.