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Re: What are units-of-measure? e.g., what's a "kilometer"?

• To: "Roger L. Costello" <costello@m...>
• Subject: Re: What are units-of-measure? e.g., what's a "kilometer"?
• From: roger.day@g...
• Date: Thu, 17 Jul 2003 14:59:43 +0100
• Cc: "Costello,Roger L." <costello@m...>, xml-dev@l...
• Sensitivity:

At 17/07/2003 14:48:25, "Roger L. Costello" <costello@m...> wrote:
#  John Cowan wrote:
#
#  > > 2. Is kilometer a function? e.g., kilometer(Yangtze) --> 6300
#  > >    In general: kilometer(physical object) --> number
#  > >    "The kilometer function maps a physical object to a number."
#  >
#  > I think this view is the most nearly correct, but it needs
amplification:
#  > it doesn't capture that it's the *length* (rather than, say, the
#  > average depth) of the Yangzi that is 6300 km.  So we can rewrite it
#  > in terms of relations as follows:
#  >
#  > Yangzi length X
#  > X kilometer 6300
#  >
#  > where "kilometer" is a relation that maps a length (an abstract
property
#  > of a physical object) into a pure number.
#
#  So, kilometer is a function of this sort:
#
#  kilometer(length(Yangtze)) --> 6300
#
#  "kilometer is a function which maps the length of the Yangtze to 6300."
#
#  Another example:
#
#  kilometer(avg-depth(Yangtze)) --> 0.25
#
#  "kilometer is a function which maps the average depth of the Yangtze to
0.25."
#
#  The general case is:
#
#  kilometer(distance) --> number
#
#  where distance is an abstract dimension object.
#
#  How are functions represented syntactically in XML?  Given the above
#  viewpoint, this form no longer seems appropriate:
#
#  <River id="Yangtze">
#  <length units="kilometer">6300</length>
#  </River
#
#  Perhaps a more faithful representation of:
#
#  kilometer(length(Yangtze)) --> 6300
#
#  is this:
#
#  <River id="Yangtze">
#  <length>
#  <kilometer>6300</kilometer>
#  </length>
#  </River>
#

I'd go for:

  <River id="Yangtze">
     <length unit="kilometer">
       6300
     </length>
  </River>

Would you want a succession of tags marked in meters, centimetres, LSD etc?

but it's probably just personal preference.


Roger

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