I think in reality, this is probably something like "Filter by bonus id", at least that's the way I have to do it in my bag addon. The goal would be to say "I want to keep warbound ilvl 584 veteran gear from TWW S1 (it can be catalyzed for tier appearances) but I want to vendor ilvl 610 Adventurer gear from S2"

Bonus id is an interesting one to add. I hadn't considered that previously, but it would be easy to add it to the item properties and add a function for "HasBonusId()". And if there is a specific bonusID associated with certain tracks then I can add a lookup for that. Seem slike a good feature to add in next significant update.

The blizzard API doesn't really help us identify upgrade track, but we can use TooltipContains("Upgrade Level: Hero") and similar to check for specific tracks.

Turns out don't need to do bonusId tricks, as UpgradeTrack is now natively supported by the wow UI. I have added this in Vendor 6.8!