Generally, manufacturers do not change IR codes very often. Therefore, if a particular IR code works with a large number of components of a particular brand, there's no reason to list every model from every year. If they did so, the program would end up being huge and 90% of it would be redundant.
In the case of your components, the RX-V1300 is in the database (near the end of the list, just before the generic Yamaha codes) and you should be able to use the RP-91 codes for your RP-56.
Mike
www.SurfRemote.com