In the schedule I looked at, P&T was not marked as HD.
Except for P&T, I rarely see a program on Showtime that is not HD. Their schedule shows a few more, and the occasional movie, but I rarely tune in and hit those.
Their on-line schedule differentiates between "TrueHD" and "Upconverted." Except for P&T, and the occasional comedy act, they rarely show an upconverted program during prime evening hours.
http://www.sho.com/site/schedules/hdtv.do?scope=thisweek&sort=time&filter=all
Okay, you're right - I was foolishly assuming that Showtime provides the same information to Tribune listings service that they publish on their own web site. So, I'm referring to the Tribune listings of Showtime, and Tribune's (HD) markings. Tribune does not just mark every program on HD channels automatically with (HD), so there is clearly some disconnect going on.