He mean backpack i think, and this backpack can only take one item type like "claws of attack +15"
like Silkroad(mmorpg) there is a horse for trade can only take items for traders you cant put your items to horse
That sort of contradicts what your first post said.
"One bag system" = An inventory of some sort
"that only carry one item type" The key words here are "One item type". Thus it is assumed you only want it to be able to contain one item.
To be more specific, an Item Class is a group of items. Charged, Purchasable, Artifact, Permament, Misc, Campaign, Powerup. Which each in turn hold Item Types, which are individual items. Belt of Giant Strength, Red Drake Egg, Health Stone, Heart of Searinox.
I do know this - xenforo dropped the ball by not keeping the vbulletin reputation comments as a feature. The loss of the Reputation comments data when we switched to Xenforo really was the death knell for the site when it came to all the users that left. I know I missed it so much and I got way less interested in the site when that feature was gone and I run the site.
I'm on a page about incorrect corrections, and spent the better part of like two hours trying to get someone to understand that -5^2 = -25, not 25, and then that post had comments get reposted because that group is self sustaining, and that person was in turn trying to explain what I just explained to them. And I'm taking that as a victory