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Michael Everson wrote on 2000-02-11 12:50 UTC:

*> >But these countries manage to trick us into using their units, world-
*

*> >wide. E. g., everybody seems to dubb 90-mm floppies as "3½-inch
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*> >floppies" (though their diameter is endeed 90 mm, exactly).
*

*>
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*> The box here next to me says 3.5"
*

Just for the record: ANSI X3.171-1989 here next to me says that the

outer dimensions of the familiar cartridge are 90.0 x 94.0 x 3.3 mm and

that the magnetic disk material itself has a diameter of 85.80 mm.

Indeed, nowhere in the drawings appears a measure of 3.5 inches.

Peter Westlake <peter@harlequin.co.uk> wrote:

*>Why are fractions only usable with Imperial units? Do ISO standards
*

*>forbid metric units to be written as fractions?
*

ISO 31-0 strongly suggests that SI units should be used only with

decimal fractions, because this significantly increases user convenience

and safety. It is obviously much easier for humans to compare 0.2734375

and 0.28125 than 35/128 and 9/32. Use of fractions in technical

drawings, product documentation, etc. is today widely considered to be a

gross violation of good engineering and documentation practice. Infinite

decimal fractions such as 1/3 are trivially avoided in real life by

making design dimensions multiples of a module size (such as 300 mm in

building construction) with a sufficient number of prime factors, as any

well-trained technical designer will be happy to tell you. Vulgar

fractions are as antiquated, inappropriate and useless in the 21st

century as are the inch-pound Flintstone units. It is amazing, how one

locale manages to need over a century longer to grasp this than all

others.

Good official style guides for using units of measurement are available

on:

http://physics.nist.gov/cuu/Units/

Those i18n gurus of you advising technical authors on internationally

appropriate writing conventions might especially find the following

brief text useful:

http://physics.nist.gov/cuu/Units/checklist.html

Markus

-- Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>

**Next message:**Otto Stolz: "Re: Vulgar fractions (off topic)"**Previous message:**Marco.Cimarosti@icl.com: "RE: Vulgar fractions (was: 8859-1, 8859-15, 1252 and Euro)"**Maybe in reply to:**Christopher John Fynn: "Re: Vulgar fractions"**Next in thread:**Doug Ewell: "Re: Vulgar fractions"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ] [ attachment ]**Mail actions:**[ respond to this message ] [ mail a new topic ]

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