75.1202-1—Temporary notations, revisions, and supplements.
(a)
Mine maps shall be revised and supplemented at intervals of not more than 6 months.
(b)
Temporary notations shall include:
(1)
The location of each working face of each working place;
(2)
Pillars mined or other such second mining;
(3)
Permanent ventilation controls constructed or removed, such as seals, overcasts, undercasts, regulators, and permanent stoppings, and the direction of air currents indicated;
(4)
Escapeways and refuge alternatives designated by means of symbols.
Code of Federal Regulations
[35 FR 17890, Nov. 20, 1970, as amended at 73 FR 80697, Dec. 31, 2008]