I can neither confirm nor deny the presence of nuclear weapons in a U.S. military installation, either! Or that the sharp-looking military aide walking a few steps behind the President is carrying the SIOP (The
Single
Integrated
Operational
Plan, the holy of holies of all military secrets, also known as the 'nuclear football'.)
Seriously, though, there are some fraternities and sororities that instruct their members not to reveal any detail about their ritual and secret work to anyone not a member. And that includes whether the ritual is printed or not and specific items of ritualistic regalia used in their ceremony.
My fraternity does print its ritual and issues a limited number of numbered copies to each chapter. There are certain parts that are transmitted only 'mouth to ear' and do not appear in any detail. Making copies of any part of the ritual book is strictly prohibited, even for the internal use of the chapter to practice.
The only public ceremony in which ritualistic robes are used in Alpha Sigma Phi is the Black Lantern Processional. All members wear black hooded robes except for the marshal, who wears white. All carry black Diogenes lanterns (or in a pinch, a kerosene lantern) and march in a slow, funereal cadence. Some chapters use the processional to pick up the candidates for initiation, others use it as a memorial for brothers who entered Omega chapter. There are other robe colors used in the ritual (not in the Black Lantern Processional), but obviously I am not at liberty to discuss them.