2H<>1H+Shield toggle

[Ynir]

The syntax for using an itm on an action bar from a macro is given in an example I found as

/script UseAction(ActionID, x, y);

"Itm must be placed in the action bar at the slot given by ActionID. ActionID is a number from 1 to 120. Slot1-ActionBar1 is ActionID1, Slot12 is ActionID12, Slot1-ActionBar2 is ActionID13 and so on up to Slot12 of ActionBar10. "

Presumably x is the slot number and y is the bar number, but the example does not make this clear. I have not tried this, not having insufficient slots on my action bars for itms.