NEF is a FAA generated program. Bascially its a lower level MEL/CDL. Not sure, but I dont think any type of parts ordering problems have to do with the NEF program. But i've been wrong in the past........
From the FAA website --- Vol 4, Chap 4, Section 7
1255. NONESSENTIAL EQUIPMENT AND
FURNISHINGS (NEF). NEF are those items installed on
the aircraft as part of the original type certification, supple-
mental type certificate, or other form of alteration that have
no effect on the safe operation of flight and would not be
required by the applicable certification rules or operational
rules. They are those items that, if inoperative, damaged, or
missing, have no effect on the aircraft’s ability to be oper-
ated safely under all operational conditions. These nones-
sential items may be installed in areas including, but not
limited to, the passenger compartment, flight deck area,
service areas, cargo areas, crew rest areas, lavatories, and
galley areas. NEF items are not items already identified in
the MEL or CDL of the applicable aircraft. They do not
include items that are functionally required to meet the certi-
fication rule or for compliance with any operational rule.
The operator’s NEF process shall not provide for deferral of
items within serviceable limits identified in the manufac-
turer’s maintenance manual or operator’s approved mainte-
nance program such as wear limits, fuel/hydraulic leak rates,
oil consumption, etc. Cosmetic items that are fully service-
able but worn or soiled may be deferred under an operator’s
NEF process.