To prevent the loss of significant data when it is
recorded on several forms, each maintenance action
must be assigned a unique identifier. Under MDS, this
identifier is known as the job control number (JCN). It
consists of a five-character unit identification code
(UIC), a four-character workcenter code, and a
four-character serial number called the job sequence
number (JSN). Figure 7-13 shows an example of a JCN
log used to record the JSNs. This system gives a
workcenter at least 9,999 JCNs. If additional JCNs are
desired, letters can be substituted for the first numeral.
In any event, take care to make sure that two different
jobs are not assigned the same JCN.
There are many different situations that could be
covered by the MDS documents. This text will cover
only the basic actions.
SHIP'S MAINTENANCE ACTION FORM
(OPNAV 4790/2K)
The ship's maintenance action form (OPNAV
4790/2k) (fig. 7-14), printed on a single sheet of
"no-carbon-required"
paper,
is
the
basic
MDS
document. If multiple copies are needed, the necessary
number of forms may be fastened together and filled in
at one time. The form may also be reproduced on
electrostatic (Xerox-type) copying machines.
This form contains six sections that require entries
to describe the type of maintenance action being
reported. Entries should be printed in capital letters. All
entries must be legible and should be inserted within
the tic marks. If an error is made, it should be lined out
using a single line, and the correct information entered.
7-22
Figure 7-13.—Example of an job control number log.
