This is concerning two items:
1. The inclusion of the term significant digits in FPLA/FDA labeling; I
believe it has no place there.
2. The name of units.
The sig dig's: As we know, "the number of significant digits" is a phrase
that indicates several related issues. Foremost, it indicates how many
digits in a value can be verified by a measurement performed by the intended
instrument. In other words, the accuracy and precision of a measuring device
used to verify the last digit in a number will determine how many digits are
significant.
To illustrate, a value of 19.000 mm indicates 5 significant digits, which
would be appropriate if it reflects the measurement obtainable from a
micrometer. A value of 19.0 mm has three significant digits, which would be
appropriate for verification by a cheap calipers or high quality
tape measure. A value of 19 mm has two significant digits and it would be
appropriate for measurements in carpentry. And the number might
appropriately be rounded to one significant digit, 2 cm, if the information
is intended to reflect a rough measurement, a guess, or a situation where
the ease of remembering is more important than precision.
In calculated numbers where the accuracy of the verifying instrument is not
known, the number of significant digits in the result must not contain more
digits than was in the least precise number. (Precision reflects the no. of
sig. dig's and vice versa.) Similarly in conversions, the result must not
contain more sig. dig's than the original number but may contain fewer when
it is apparent from circumstances that an original number had exaggerated
precision.
Here is a refresher on significant digits and indeterminability (many had
seen this before).
There are three significant digits in a number like 77.8; five in 789.30;
one in 0.07; two in 0.071; four in 500.0, five in 10.302. The significance
is indeterminate in numbers such as 2000, or 20. Notice that prefixes make
it often easy to remove the indeterminability. Compare 2000 kW vs. 2 MW;
whereas the former is indeterminate (1, 2, 3, or 4 digits may be
significant, we do not know), the latter can be understood as more than 1.5
but less than 2.5. In calculations, the number with the fewest of sig. dig's
determines the outcome. To illustrate, 17.5 m in 2 s is 9 m/s, whereas 17.5
m
in 2.00 s is 8.75 m/s.
Instruments used for the determination of the numbers on a nutritional label
can verify far more significant digits than the public needs to be shown.
Similarly, the ingredients - they could be specified more closely but it is
not needed. On the contrary, it is desirable that the numbers on labels are
as simple as possible which implies also the avoidance of the decimal marker
wherever practical. Thus many of those numbers fall into the indeterminable
category, such as 300 mg, 350 mg, 500 cm³, 2070 kJ, etc.
Therefore, I would drop the word "significant" and suggest instead:
" ....select a prefix that will enable a value to be expresses with no more
that 3 or 4 digits. The 3 digits count is preferred. The 4-digits count is
to be used only if it is needed to retain the same prefix in a column of
numbers. For example, 1000, or 2070 with 870. In the 4-digits number there
will be no space or any other divider between the first and the second digit
(counted from the left)."
The above paragraphs suffices. There is no need to go into "significant
digits" in the FPLA/FDA regulation as it applies to labels on products on
supermarket shelves.
As a side issue, I see on many labels the unit in brackets with the
quantity, e.g.,
mass (mg) ..... 320.
I wonder if that ought to be considered although personally I am not in
favor of it despite the advantage it has in some circumstances.
Now the second issue. I believe the addition of names is a mistake. There is
not room for it on labels; every one label in my world-wide collection uses
symbols only; it is obvious that containers with nutrition labels are
exported/imported - not everyone speaks English, nor everyone uses the Latin
script/alphabet. Any imbecile knows those symbols by now. Why would we want
to introduce words where there was a simple and sufficient info in use from
the beginning of the labeling?
Here it is again as it was in Gene's original in the KIS principle.
(3) (A) (i) .......shall be expressed in g or its multiples;
(ii) ...........of linear measure, shall be expressed in m or
its multiples;
(iii) ...... of area, shall be expressed in m² or its multiples;
(iv) .... of volume, shall be expressed in m³ or its multiples, or
ml, mL or l or L.
Stan Jakuba
