All good points! -- except the admitting defeat part. ;-) The ever-unfolding wonder of PM is the diversity of approaches to any given problem and the discussions that they stimulate. We all win as a consequence. Frankly, I didn't really consider my method to be that innovative, hoping instead to employ (and learn about) hash slices in lieu of the grep -- but to no avail. Nonetheless, what resulted was different enough, and it worked -- subject to the very real limitations you point out. Thanks and ++ to BrowserUK for troubling to do the efficiency analysis that I was too lazy to perform!