A session handler must be specified for the session. The session handler is provided by Teraspaces to implement business logic of the order management. Handlers with name from "_Standard40" to "_Standard50" are standard implementation of FIX order handling logic from FIX 4.0 to FIX 5.0.
Teraspaces can implement custom session handlers to help clients with non-standard order handling logics. Those non-standard order handling logics are usually bugs but we can work around with our costom made handlers.
Different versions (schema) of FIX protocol define different (though slightly) order handling logics. In FIX session transport protocols before FIX 5.0, only one version of schema is supported per FIX session. However, starting from FIX 5.0, more than one FIX versions can be supported in one FIX session, with the new FIX transport protocol.
The Order Manager settings editor is able to assign handlers to different schemas in a FIX 5.0+ session.