50-73-206. Maps to be updated on basis of semiannual surveys. An extension of the last preceding survey of every mine in active operation shall be made once every 6 months, and the result of the survey, with the date, shall be promptly and accurately entered upon the original maps so as to show all changes in plan or new work in the mine and all extensions of the workings to the most advanced boundary of the workings which have been made since the preceding survey. The changes and extensions shall be entered on the copies of the maps of the department or new copies furnished it within 30 days after the last survey is made.