IFF tags

IFF tags they are very much apart of the halo canon as MA5’s and sweet Williams cigars but one thing that’s really confusing is where are they located halo nation and halopedia say there in the armor which would explain how they come up without a helmet but then forward unto dawn says their in the helmets of the cross branch battle dress uniforms being field tested in the sector that corbulo academy of military science is in and the last reference that I know of is the fall of reach which has it implanted in the back of the skull now I’ve heard references of people taking out their IFF tags to confuse the enemy which makes no sense if its in their skull which is also more con fusing by the fact that in the level infinity there are IFF tags laying all over the place so where are the IFF tags placed and if its not in the back of the skull what is in t chiefs skull that makes adjustments to so he could link with the mijolnir mark V powered assault armor? thanks if you can answer that.