Jim,

You raise an excellent point. Let me elaborate the point with the usual
caveat and disclaimer that I am not a lawyer. However, this may prove to
be a useful "short guide" to various documents and may help put things
in perspective.

1.      SI 10 is an American National Standard. It has the status of a
voluntary standard (invokable by contract, of course) of industry. There
is no federal declaration of SI 10 as a federal regulation or law, so
unless invoked by contract it has no legal standing. That does not
impugn its value, however, since it is widely recognized throughout
industry! And that industry crosses our American national boundaries,
via IEEE's international membership. Roughly, the ISO standards are on
an equal footing with this document, though in some countries ISO
standards are also invoked as national standards. Bottom line: SI 10 is
something that a large portion of industry has agreed to abide by.

2.      We also have the DoC/NIST Federal Register notice: Metric System of
Measurement: Interpretation of the International System of Units for the
United States [63 FR 40334-40340, 1998 July 28]. The USMA home page
provides a link to a pdf copy of this notice. This is the legally
binding federal regulation in the United States. To assist people in
using this, the DoC/NIST folks have also provided guidance in the form
of Special Publications 330 and 811, among others. Bottom line: this is
the law of the land, regarding the metric system, in the United States
of America and as such conveys some national differences from the SI
brochure, "Le Syst�me International d'Unit�s".

3.      The BIPM, on behalf of the CGPM publishes a brochure, "Le Syst�me
International d'Unit�s", which is the international authority across all
fields of commerce, in all fields of science, and for all signatory
governments. It is actually a document of state, arising from an
international treaty, "La Convention du M�tre". The brochure is
published in two languages, as are many international documents of
state, French and English, the primary and secondary languages of
diplomacy. The French version takes legal precedence. Bottom line: this
is the international, defining document for the SI.

Now to the point of discussion. Nowhere in the brochure (paragraph 3,
above) is there an explicit statement requiring a space between numbers
and units. Yet, that is the way the brochure is written, so one might
see this as "tacitly suggestive". However, SI 10 (paragraph 1, above)
does require a space in its normative (i.e., "mandatory") text. Likewise
NIST SP 811 also explicitly requires a space between number and unit,
though SP 330 (essentially an American national "translation" of the SI
brochure) does not. The federal notice (paragraph 2, above) also
requires a space in "Rules and Conventions", number 12 (page 9 of the
pdf file; page 40340 in the Federal Register cited).

Bottom line: The space between number and unit is specified in US
federal regulations and guidelines; an American National [industry]
Standard, SI 10, which is used internationally; and other industry and
national standards, such as ISO perhaps; but not by the international
organization that defines the SI. Thus, the SI does not require the
space, though many implementations of it do.

I hope this helps people here understand the legal relationships of SI
standards, at least as I perceive them. Subject to correction of the
above, this might be worthy of being posted on my web pages.

Jim

Jim Elwell wrote:
> 
> At 09:20 PM 2/8/2002 -0500, James R. Frysinger wrote:
> >The presentation is generally very good, once one remembers that a space
> >between numbers and units are not required.
> 
> My copy of SI 10-1997 says the space is required. Why do you say it is not?
> 
> Jim

-- 
Metric Methods(SM)           "Don't be late to metricate!"
James R. Frysinger, CAMS     http://www.metricmethods.com/
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