Numbers were allotted as follows: Architectural 101-199 Civil 201-299 Electrical 301-399 Mechanical 401-499 Sanitary 501-599 Structural 601-699 Surveys 701-799 Miscellaneous 801-899 Working drawings were given numbers consisting of one-digit or twodigit number, a letter, a dash, and a three-digit number. The first element indicated the use feature of the work. Use features were assigned numbers as follows; Site Plans 1 Buildings 2 Special Structures 3 Power Plants 4 Refrigeration 5 Electrical Distribution 6 Communications 7 Signal and Control 8 Water System 9 Sewer System 10 Fuel System 1i Airstrips 12 Roads 13 Grading and Paving 14 Subaqueous 15 5-15