UA has eroded heaviy for 3 years running now the TYPE of tickets a SWU can be used on.
2 years back pretty well anything you could buy was UG with SWU. RTW, nett fares, consolidator fares, circle pacific, etc. I do not have the older certs in front of me now as a FT'er who wanted them for a 'non-published' fare is using them next month but pretty sure 'S' was OK on them. Some FT'ers still have 2001 wording SWU valid for use until this year, and I had some of those. Mote detail here:
http://www.flyertalk.com/forum/Forum50/HTML/014576.html