  This paper describes a simple quantitative test applicable to current-voltage
data for cold field electron emission (CFE). It can decide whether individual
reported field-enhancement-factor (FEF) values are spuriously large. The paper
defines an "orthodox emission situation" by a set of ideal experimental,
physical and mathematical conditions, and shows how (in these conditions)
operating values of scaled barrier field (f) can be extracted from
Fowler-Nordheim (FN) and Millikan-Lauritsen (ML) plots. By analyzing historical
CFE experiments, which are expected to nearly satisfy the orthodoxy conditions,
"apparently reasonable" and "clearly unreasonable" experimental ranges for f
are found. These provide a test for lack of orthodoxy. For illustration, this
test is applied to 17 post-1975 CFE data sets, mainly for carbon and
semiconductor nanostructures. Some extracted f-value ranges are apparently
reasonable (including many carbon results), some are clearly unreasonable. It
is shown that this test applies to any field-emission diode geometry and any
form of FN or ML plot. It is proved mathematically that, if the extracted
f-value range is "unreasonably high", then FEF-values extracted by the usual
literature method are spuriously large. Probably, all new field-emitter
materials should be tested in this way. Appropriate data-analysis theory needs
developing for non-orthodox emitters.
