Re: [xml-dev] ANN: a portable data component -- length

[Stephen D Green <stephengreenubl@gmail.com>]

On 9 April 2011 18:58, Frank Manola <fmanola@acm.org> wrote:
> Certainly it sometimes makes sense to provide "redundant" data in this way.  But do you really (a) provide the values in multiple units, (b) provide the conversion factor, and (c) check the values for validity using the conversion factor, which is what is being proposed here?  For example, if you're providing prices for both imperial and metric weights, the prices ought to be in integral units of currency/coinage that people actually carry (no hundredths of shillings), and the weights some values that people in grocery stores can actually measure, right?  And do those numbers really work out so the exact same numbers appear on both sides of the conversion equations?

Well, we are definitely getting away from the point of Roger's
thesis, that there are some statements made via XML markup
that have requirements constraining how they relate to each
other. My own contributions was to suggest a somewhat
metaphorical example of prices expressed in different units.
This is because I come from a business document domain
and am familiar with price lists, invoices, orders, etc. Plus
Roger's example was loosely connected to this via books
which are a bit like products and booklists which to me are a
bit like price lists. It is stretching the domain a bit to use the
example of measures variously expressed in various units
but there are so many ways that measures and units are used
in marked-up documents that we don't have any trouble keeping
it real because there are so many scenarios to pick from. In
actual fact my other domain of some exposure is that of
specifications and test assertions relating to them and here
there are definite cases where there is a need to express the
same statement in various ways - such as internationlisation.
I can assert that a device has certain requirements regarding
voltage in one country and related but different requirements
regarding voltage in another country due to the differing mains
voltages but the matter of conformance to the spec which
covers both countries at once means these requirements have
to be unambigous. So it might be that the values for conformance
are stated in the spec for every country separately or for every
voltage separately or it might be that the voltage is made a
variable and the requirements are expressed in terms of this
variable. In each case it is an overall aim in writing both spec
requirement statements and corresponding test assertions that
each requirement is self-contained and atomic (I learnt this from
the spec conformance experts) sp that a test case can relate
to just one specific requirement in the spec via the test
assertion. That all seemd a bit too involved for Roger's example
though.

----
Stephen D Green