I'm thinking about using OpenEMM as a back end using its web service functionality coupled with a separate, custom-made front end.
I was wondering if the additional terms regarding adding the OpenEMM logo and copyright notice on each user interface screen (http://www.openemm.org/cpal1/openemm.html) applies in this case.
You have to show copyright and logo only in modified JSPs. If you write your own frontend from scratch you do not have to do that. However, you must keep the copyright notes in the backend files if you modify them.