The last line of tonym's post really should read:
no matter which direction we go it WILL be a great undertaking
Obviously, the bulk of the material affected by the topic of this thread occurs in the Non-Sports section of the site. When I go to the Name Validation section (under Things to do), there are currently almost 14,000 sets that need the names to be validated*. Of those, 11,500+ are in Non-Sports. Mostly, because we're unsure of the way to go with these (I guess).
Personally, I have added the zero PID to several sets (all cards). If we changed things now, they would need to be reversed (which if that's the way it goes, cool). I know that there are still thousands of sets that should get this treatment if we stay the course.
My opinion: PIDs were set up so that cards of particular individuals would be identified. (Same as the TIDs for teams.) This makes for ideal database usage. PID stands for Person IDentifier. We've taken that and added to it Stadiums, Landmarks/Monuments, Comic Book characters, etc. Maybe not the original intent behind it, but then again, this site has been doing a lot of evolving over time (and this is a great thing). I don't think we should stray too far from where we are now with the rules for when a card subject gets a PID and when one doesn't.
That said, a system of "Subject Tagging" could be a very useful thing - however - it could and probably would be a very, very incomplete thing. Let's take, for example, a random 1985 card of Dale Murphy. What are the different tags it could get? "Braves", "BYU", "Mormon", "MVP", "Outfielder", "White Border" (Topps), "Black Border" (Donruss), "Home Uniform", "Away Uniform", "Holding a Bat", "Wearing a Glove", etc. Where do we draw the line? There are literally infinite possibilities. Big picture, I don't see this ending well. (Heck, I don't see it ending, period.) Even limiting a new tagging system to Non-Sport doesn't limit the possibilities. (And besides, if you collect - or want to tag - squirrels, I know there are 2 squirrel cards in baseball.)
This concept of a new tagging system is a really good idea, could be beneficial to many collectors, and has a lot of potential. However, there still are some major wrinkles that need to be thought through and taken care of before implementation can even be entertained. Please, let's keep the dialog going so we can resolve these issues (or determine that they cannot be resolved).
-- Dan --
Note: Please see my profile for more info regarding trading (section updated 3/4/2024). I have added a large portion of my inventory to the site, and currently have trading turned on (details are in my profile).