What is the meaning of the tab in clergy attire?

Answer 1

Aclerical collar is a piece of clerical clothing. It is a detachable collar that buttons onto a clergy shirt or Rabat (vest), being fastened by two metal studs, one attached at the front and one at the back to hold the collar to the shirt. The collar closes at the back of the neck, presenting a seamless front. It is almost always white; and was originally made with cotton or linen but is often made with plastic now. Sometimes (especially in Roman Catholic practice) it is attached with a "collaret" or "collarino" that covers the white collar almost completely, except for the top edge and a small white square at the base of the throat, to mimic the collar of a cassock. Sometimes the collar is black (or whatever color is appropriate to the rank of the clergyman), with only a detachable tab of white in the front.