I would like to propose this new macro feature:
We have [exists] or [noexists] for target players to checdk if they exists or not!
Then we have [equipped] or [noequpped] to check for gear if it s equipped or not

My suggestion is ( and this because i was trying to make a macro and cant beacause this condition doesnt exists):

[itembag] [noitembag] for a condition when there is or not an item in bag.

The macro i was trying to do, and that can be made with this was:

/use [itembag:Mana Emerald] Mana emerald; mana ruby

this is so i can conjure 2 gems.. and if there is a emerald in bags i use emerald .. if not i use ruby!

/castsequence mana emerald, mana ruby , this one works but with a problem when i use mana emerald i have to use mana ruby first before using new mana emerald, else even if i have mana emerald in bags it will use ruby 1st and then reset back to emerald!

My suggestion is to show mercy on your Caps Lock button.