On Apr 5 , at 5:47 PM, <[email protected]> <[email protected]>
wrote:
(A) (i) if on a package, labeled in terms of mass, shall be
expressed in g or its multiples;
(ii) if on a package labeled in terms of linear measure, shall be
expressed in m or its
multiples;
(iii) if on a package labeled in terms of area, shall be expressed
in m2 or its multiples;
(iv) if on a container labeled in terms of volume or fluid measure
shall be expressed in m3 or
its multiples, or ml, mL, or L.
Sorry, but I can't agree that units symbols should be used in place of
unit names (written out) in text material. Unit symbols are "symbols"
and should be used with symbols, like "25". All numerically written
numbers are symbols. "25" is a symbol, "twenty-five" is a word. Thus
write "twenty-five metres" or write "25 m" but generally avoid writing
"twenty-five m" and "25 metres". (I admit that the latter is commonly
accepted.)
The normal extension of that, from the SI point of view, is that unit
symbols are not intended to be used with words in ANY situation, such
as the above quoted material from Gene Mechtly. It should say "...
expressed in grams ...", definitely not "... expressed in g ...", and
likewise in all the other examples in his text.
This has to do as much with good writing style as it does with SI. I
may have to interpret the intent of the SI rules to make my case, but
the writing style rules are clear. Good writing does not allow words
to be supplanted by symbols except where the symbol is part of an
expression that is normally written that way.
One does not report a medical check-up by writing "I saw the Dr.
today" nor "It only cost a $ to buy the magazine". We write "I saw the
doctor today" and "It only cost a dollar to buy the book".
However, since "Dr." is traditionally used as part of a title, it is
proper to write "I saw Dr. Smith today". Also, since "$" is typically
used to express amount of money in dollars, it is proper to write "It
only cost $1 to buy the magazine."
The rule for most of the above could read:
"Use words with word and symbols with symbols, no mixtures."
That would cover the above situations and also some other annoying
uses like the following.
Bad and common:
kilometres/hour
(which is in the form of word-symbol-word)
Less common but equally bad:
km per hr
(symbol-word-wrong symbol),
and worse yet but unfortunately quite common:
kph
(wrong symbol-abbreviation-symbol)
The only acceptable forms are:
all in symbols,
km/h (as in "The car went 85 km/h down the road.")
and
all in words,
kilometres per hour (as in "The speed limits are posted in
kilometres per hour.")
Bill Hooper
body mass*
73 kg
seventy-three kilograms
Fernandina Beach, Florida, USA
* plus or minus a kilogram or so.
(NOT plus or minus a kg or 2 !)
