A "Mandatory Sign" means a sign prescribing behavior.
Mandatory Signs are not, as some people believe, 'those which are required by law'. Mandatory signs are used for identifying something that must be followed.
These are waterproof, durable and can range from personal protective equipment required when on building site, such as hard hats and high visibility jackets.
These signs are for informing the users about the specific laws & regulations to ensure safety and to make sure about the clear movement of traffic. As the name itself says mandatory, that means any violation of these signs will leave you in trouble and that will be considered as a legal offence. These signs notify a person about the special obligations, prohibitions and the restrictions.
Most of the signs under this category are round shaped, may get the symbols painted white on a blue background, having a white border or maybe there is a white background to carry black symbols with a red border. However, the last mentioned may also be associated with restrictive signs. Here’s the list giving the meanings of mandatory signs.

Standard Sizes : 6x6 in, 8x8 in, 4x12 in, 8x24 in, 8x12 in, 16x24 in

Types	6x6 inch	4x12 inch	8x8 inch	8x12 inch	8x24 inch	16x24 inch
Sticker Only (Rs. 2/sq. in)	Rs. 72	Rs. 96	Rs. 128	Rs. 192	Rs. 384	Rs. 768
Sticker on Sunboard / Rigid Plastic (Rs. 3/sq. in)	Rs. 108	Rs. 144	Rs. 192	Rs. 288	Rs. 576	Rs. 1152
Both Side Sticker on Acrylic or ACP (Rs. 6/sq. in)+100	Rs. 316	Rs. 388	Rs. 484	Rs. 676	Rs. 1252	Rs. 2404