T.O. 31 S5-4-898-4
USABLE ON CODE Column. Part variations within groups or models are identified by a code (consisting of
letters of the alphabet) in the USABLE ON CODE column. The absence of a code indicates that the part so shown is
usable as a replacement on all groups or models covered by this manual.
Usable On Code
Serial number 101 thru 123
Serial number 124 and up
g. SMR CODE Column. This manual contains Joint Military Services Uniform SMR codes. Definitions of these
codes are available in T.O. 00-25-195. By referring to the SMR codes, the user can determine whether a part should be
requisitioned, manufactured, or is nonprocurable.
SMR codes which are preceded by a plus (+) apply to the Air Force and Army only. Associated Marine
Corps SMR codes for identical part numbers are listed in the numerical index (Section III).
SECTION III - NUMERICAL INDEX. The numerical index is an alphabetical listing of all of the part numbers listed
in the MPL PART NUMBER column. Also included are assigned national stock numbers (NSN) or class codes; figure and
index numbers; the total quantity per end item; and the SMR code, special stockage indicator (SSI) code. and
replacement (REPL) factor for Marine Corps items.
a. PART NUMBER Column. This column lists all of the MPL part numbers, in accordance with the following
order of precedence.
First position order:
(a) Letters A through Z
(b) Numerals 0 through 9
Second and succeeding position order:
(c) Letters A through Z
(d) Numerals 0 through 9
b. NSN Column. This column lists the national stock numbers, if assigned, for centrally managed parts required
to support the disk memory unit. The NSN is a unique identifier, independent of the manufacturer, used for ordering
replacement parts from the supply system. If an NSN has not been assigned to an applicable part number, a four-digit
class code will appear in the NSN column, identifying the type of part (resistor, capacitor, etc.) described. When NSNs
have been assigned. they should be used in all supply operations, from original purchase to final disposition. The
absence of an NSN indicates that the part is not normally stocked as a repairable item. If a part is required which has not
been assigned an NSN, use the SMR code to determine if that part can be obtained from other sources. Items not stock
numbered, which cannot be obtained from other sources, may be requisitioned using the FSCM and the manufacturer's
c. FIGURE & INDEX NUMBER Column. This column lists the numerically assigned figure and index numbers
for each illustration. When an assembly or part has not been assigned an index number, the figure and index number of
the preceding part in the MPL is used with the letter F (standing for follows) preceding the figure number; for example, F7-
d. QTY PER END ITEM Column. The quantities listed in this column are the total quantities used per disk
memory unit. For totals of specific piece parts under separate indentation, refer to MPL UNITS PER ASSY column in