You
can customize only those function strings that are not in the rs_default_function_class function-string
class.
For functions with replication-definition scope:
The DSI uses rs_default_function_class for
functions that do not use a table or function replication definition
with the send standby clause.
Otherwise, the DSI uses the function-string class
associated with the connection.
For functions with function-string class scope, the DSI always
uses the function-string class associated with the connection.