When Chicago first debuted (is that redundant?), some rock purists were hesitant to call it a "rock band" because it had a built-in horn section (Jimmy Pankow on trombone, Lee Loughnane on trumpet, and Walter Parazaider on saxophone and flute).  Here, Dan Markus (a trombonist himself-back in the day) brings the subject up with Chicago founding member Jimmy Pankow.