T.O. 31 S5-4-898-4
e. USMC SMR CODE Column (Marine Corps only). This column lists the SMR codes which are assigned to
parts subordinate to or associated with an end item; that is, spares or repair parts. The uniform code format is comprised
of three parts: a two-position source code; a two-position maintenance code; and a one-position recoverability code. The
SMR code provides the user with the following iniforliation for each part:
Method (source) of obtaining the part; for example, by requisition, fabrication, or salvage.
Maintenance and recoverability codes are not applicable when the following source codes are used: XA, XB, and
(2) The lowest maintenance echelon authorized to remove, replace, and use the part; and the lowest
echelon capable of performing a complete repair.
(3) Disposition (recoverability) action on unserviceable parts.
The numerical index USMC SMR CODE column lists Marine Corps codes only. Refer to MPL SMR CODE
column in Section II for Air Force/Army codes.
USMC SSI CODE Column (Marine Corps only). This column lists the conditions for stocking unique
maintenance parts (those assigned NSNs and coded in the P series (source) of the SMR code). The SSI codes are as
(1) No code - indicates that the part may or may not be authorized in initial allowances to using or
supporting organizations. The initial allowance is explained in the REPL Factor description which follows.
(2) I - applied to maintenance parts for which predicted consumption would not warrant inclusion in mount-
out but, for which a quantity of one is authorized as insurance for mount-out using a 360-day criteria based on the total
density of equipment employed by the DIV/WING team. Mount-out allowances, so authorized, will be stocked by the FSR
or MWSG for Marine wing peculiar equipment, as applicable.
(3) D - applied to maintenance parts that are not considered critical or essential stockage; therefore, they
are not authorized in initial allowances However, these items are stocked within the supply system and may be
requisitioned when needed.
(4) T - indicates that the part is authorized m garrison operating allowances to comply with state and local
laws; however, the part Is not authorized in mix,. ,t-out since it is not combat essential.
g. USMC REPL FACTOR Column (Marine Corps only). This column lists the replacement factor assigned to
each national stock numbered maintenance repair part. The REPL factor is a decimal number which indicates the
average rate at which the type of part so coded has been used by Marine Corps field units, or the rate at which design
engineers anticipate the part will fail, wear out, or otherwise require replacement. All computations are based on a
replacement period of 1 year.
(1) Initial authorized stockage levels of consumable and salvageable parts for an organization are to be
computed for predicted consumption based on the number of parts employed and/or supported by an organization within
the number of days for which stockage is authorized. In computing garrison operating stock or mount-out, authorized
levels can be determined by the requiring Marine Corps unit by multiplying the REPL factor times the quantity used per
equipment times the number of end Items employed by the using organization or supported by the service organization
times the authorized day level expressed in months and divided by 12. Specific formulas and examples are provided in
Marine Corps Order (MCO) P4400 79. The REPL factors used in initial stockage computations should be revised, if
warranted. after significant usage is experienced, in accordance with guidelines of MCO 4400.32A. Use the following
formula for revising the REPL factors based on actual usage. W equals the revised REPL factor. X is the usage
experience of 1 year; A is the application per equipment; and B is the number of equipments supported.