so since now I'm getting PMs despite answering this here with examples.
Let's say you are wanting to tank and swap to assist at some point. Your best bet would be not being group leader (this will save you a step in your hotkey/social whatever - since if you are in a tank mode and are group leader you will currently assign yourself as such).
So now you're not group leader (to save step) and NOT assigned as group main tank in the group window
you want to do tank stuff - you can
/shd mode 4 or
/she mode 7 or whatever tanking mode you want to be in - and now you're doing defensive tank stuff
you no longer want to do tank stuff - you can /shd mode 0, 1, 2, 3, 6 and now you are in one of the assist modes and since you are in an assist mode and not assigned as main tank - you will your non-tanking routine
Tank/NotTank Swapping Checklist of Amazinglyness:
Not Assigned as Group Main Tank in the Group Window
Not Group leader (so you don't auto assign yourself roles)
Then a couple of social hotkeys can make swapping easy.
(I like tossing in a resetcamp as going from one camp mode to another does not remove/recreate your camp - doing the resetcamp would allow you to have your camp set to right where you are now, for example)
DerpTank7
/shd mode 7
/shd resetcamp
DerpAssist1
/shd mode 1
/shd resetcamp
Alternatively, if you didn't want to have someone else be the group leader you could have another line in your social to utilize the everquest grouproles commands to un-assign yourself as group main tank since a tanking mode and group leader will assign you as group main tank in the window as previously mentioned -
you would just use either a saved group roles set, or just unassign the tanking group role