Section 27(10)(f) in The Merchant Shipping (Crew Accommodation) Rules, 1960
(f)The pans shall preferably be made of white vitreous china or other suitable material. They shall be of an approved pattern complete with foot holds designed to prevent shipping. The orifice at the top of the pan shall be not less than 41.85 centimetres in length and not less than 23 centimetres in width. The pan shall be placed as low as practicable.