As the title says. A OS button on the bid frame so a player can signal that he wants the item for OS.
And just something that lights up for the raidleader.

I always have to ask on discord if anyone wants an item for OS. And someone always manage to not hear it or afk or whatever. So a simple button would be perfect.

Just to be clear, i dont mean a separate OS bidding system, just something to let the Loot master know there is OS interest.

Allowing bidders to write a very short text note along with their bid is more flexible than just an "OS" indicator, but similarly easy to implement. This way guilds could also make other types of bids, for example for twinks, hybrid off-spec (heal stuff for shadow priest) etc.

Alternatively, allow the loot master to create a list of different options whose names can be customised, e.g. "MS" "OS" "PVP", and people have to select one of these options when bidding.

It would also be nice to have an option to not allow someone bidding on something for offspec to bid up an item. If we have two healers bidding on some healing pants, and a shadow priests wants to bid for offspec, right now it will allow

Healer 1: !bid 10
Spriest: !bid 20
Healer 2: !bid 30

where the second healer has to out-bid the shadow priest who is bidding for offspec. It would be nice if the shadow priest would get a declined message, like "Bid declined: There is already a main spec bid"

I'm not sure exactly how to handle it if the offspec bid is the first bid though. Maybe it could allow any main spec bid (that's >= the minimum bid) would beat it out.