TM 5-4520-256-14 B-4.  EXPLANATION OF COLUMNS IN TOOL AND TEST EQUIPMENT REQUIREMENTS, SECTION III - Continued. b.   Column  2,  Maintenance  Category.    The  lowest  category  of  maintenance  authorized  to  use  the  tool  or  test equipment. c.    Column 3, Nomenclature.   Name  or identification of the tool or test equipment. d.   Column 4, National Stock Number.  The national stock number of the tool or test equipment. e.   Column 5, Tool Number.  The manufacturer's part number. B-5.  EXPLANATION OF COLUMNS IN REMARKS, SECTION IV. a.   Column 1, Reference Code.  The code recorded in column 6, Section II. b. Column 2, Remarks.   This column lists information pertinent to the maintenance function being performed as indicated in the MAC, Section III. Section II  MAINTENANCE ALLOCATION CHART (1) (2) (3) (4) (5) (6) MAINTENANCE CATEGORY TOOLS GROUP COMPONENT/ ASSEMBLY MAINTENANCE AND NUMBER FUNCTION C O F H D EQUIPMENT REMARKS 00 HEATER, DUCT TYPE, PORTABLE, HDU-36/E 120,000 BTU/HR Air Filter Inspect .1 Service .2 Replace .2 Exhaust Pipe Inspect .2 Replace .2 Duct Assemblies Inspect .2 Repair .3 Replace .2 01 CABINET ASSEMBLY Inspect .3 Repair .8 Replace 1.0 1 B-4