yep, its a standalone programmer for the pc. no need for a digitrax dcc system to use it, only the free and open source JMRI pc software http://jmri.sourceforge.net/. but if you have a digitrax dcc system, there is a zillion possibility, from computer controlled train, to CTC dispatching or use an iphone/ipod touch as a throttle ! the programmer also allow you to load customs sound files in a digitrax soundbug decoder using a Digitrax software.
If you're just looking for a computer interface to program with JMRI, then I'd suggest that you get the least expensive one (MRC?) as they all work the same.
lack of compatibility with MRC is the only reason i'm with NCE today . unless there is unofficial modification that alows JMRI to interface with MRC proprietary comand bus, but i highly doubt.