Yes, Rocket's comment is correct. The answer is that ALL RealTracks are playable, provided that you have installed (a) Sforzando plugin (which is installed along with the main BB program), (b) HiQ Instruments, and (c) Playable RealTracks.

When you click either the PRT button in the Notation Window, or the "Playable RealTracks" button in the Piano Roll window, Band-in-a-Box will load in the best Playable RealTracks MIDI sample that is currently available. There isn't necessarily a direct one-to-one correspondence between RT and PRT. Some RT's don't have a perfect match, but it gets better over time as more PRT samples are developed.

As support mentioned earlier in the thread, if you want to see a list of HiQ and PRT samples that the feature draws on, you can look at the list of HiQ patches by right-clicking on a MIDI track. You can also look in the Sforzando Plugin Instrument --> Band-in-a-Box Sounds menu, or directly in the folder where they are located (by default):
C:\Program Files\PG Music Inc\Band-in-a-Box Sounds\Programs.

Andrew
PG Music Inc.