This could be interesting: how or for what reason this aggregation got organized is a mystery to me, but the plan is to have these four folk- and country-tinged songwriting vets up on stage with acoustic guitars, playing solo and together. John Hiatt doesn't thrill me the way he does some people, but he does have an easy grasp of a certain bluesy groove, and it'll be neat to see him solo and with this group. Guy Clark is a smart and thoughtful Texas writer who made a bunch of well-done albums that have never really gone anywhere. John Prine is a Chicago boy who's put out a bunch of great albums that have never gone anywhere either. And the same goes double for the magnificent Joe Ely, except he's from Austin. I respect all these people. Besides the show, the foursome have a (free!) songwriting seminar planned for 5:30, at the Vic as well; they'll be lecturing and taking questions. Tuesday, 9 PM, the Vic, 3145 N. Sheffield; 472-0449 or 248-7277.