Well, well, well. You know how teenage boys can be and they felt the definition of "dress" left a lot of room for interpretation. They'd wear plaid golf slacks, hawaiian shirts, and paisley ties, for example. They'd also raid their fathers' closets for the polyester 70's leisure suits. Oh they had fun.
Yeah, St. John's lets the boys have some leeway as long as they have a sport coat and tie and Dockers type slacks. There's a lot of room for interpretation there.