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Re: Schematron: Categories of Usage?

• From: "bryan rasmussen" <rasmussen.bryan@g...>
• To: "Costello, Roger L." <costello@m...>
• Date: Mon, 22 Jan 2007 13:15:42 +0100

oops, just noted I slipped into wrong terminology and where I meant to
write the upper boundary of my sequence i wrote Upper Bound,
embarassing.

Cheers,
Bryan Rasmussen

On 1/22/07, bryan rasmussen <rasmussen.bryan@g...> wrote:
> Algorithmic checking:
>
> the following checks the algorithm of EAN Location numbers, after the
> algorithm found here
> http://www.ean.dk/EAN_Sys/helpdesk/faq/kntrlcif.htm#EAN%20Lokationsnummer
> (sorry, it's in Danish):
>
> <sch:rule context="*[@schemeID]">
>    <sch:report test="@schemeID='EAN' and string-length(.) != 13">
> WARNING: EAN numbers are 13 digits in length
> </sch:report>
> <sch:report test="@schemeID='EAN' and . != (. + 1) - 1">
> WARNING: EAN numbers are 13 digits in length</sch:report>
> <sch:report test="@schemeID='EAN' and substring(.,13,1)!=0 and ((((10
> - substring((substring(.,1,1) * 1 + substring(.,2,1) * 3) +
> (substring(.,3,1) * 1 + substring(.,4,1) * 3) + (substring(.,5,1) * 1
> + substring(.,6,1) * 3) + (substring(.,7,1) * 1 + substring(.,8,1) *
> 3) + (substring(.,9,1) * 1 + substring(.,10,1) * 3) +
> (substring(.,11,1) * 1 + substring(.,12,1) *
> 3),string-length((substring(.,1,1) * 1 + substring(.,2,1) * 3) +
> (substring(.,3,1) * 1 + substring(.,4,1) * 3) + (substring(.,5,1) * 1
> + substring(.,6,1) * 3) + (substring(.,7,1) * 1 + substring(.,8,1) *
> 3) + (substring(.,9,1) * 1 + substring(.,10,1) * 3) +
> (substring(.,11,1) * 1 + substring(.,12,1) * 3)),1)) +
> ((substring(.,1,1) * 1 + substring(.,2,1) * 3) + (substring(.,3,1) * 1
> + substring(.,4,1) * 3) + (substring(.,5,1) * 1 + substring(.,6,1) *
> 3) + (substring(.,7,1) * 1 + substring(.,8,1) * 3) + (substring(.,9,1)
> * 1 + substring(.,10,1) * 3) + (substring(.,11,1) * 1 +
> substring(.,12,1) * 3))) - ((substring(.,1,1) * 1 + substring(.,2,1) *
> 3) + (substring(.,3,1) * 1 + substring(.,4,1) * 3) + (substring(.,5,1)
> * 1 + substring(.,6,1) * 3) + (substring(.,7,1) * 1 + substring(.,8,1)
> * 3) + (substring(.,9,1) * 1 + substring(.,10,1) * 3) +
> (substring(.,11,1) * 1 + substring(.,12,1) * 3))) != substring(.,13,1)
> )">
> there is an improperly formatted EAN number.
>
>
> </sch:report>
> <sch:report test="@schemeID='EAN' and substring(.,13,1) =0 and
> substring((substring(.,1,1) * 1 + substring(.,2,1) * 3) +
> (substring(.,3,1) * 1 + substring(.,4,1) * 3) + (substring(.,5,1) * 1
> + substring(.,6,1) * 3) + (substring(.,7,1) * 1 + substring(.,8,1) *
> 3) + (substring(.,9,1) * 1 + substring(.,10,1) * 3) +
> (substring(.,11,1) * 1 + substring(.,12,1) *
> 3),string-length((substring(.,1,1) * 1 + substring(.,2,1) * 3) +
> (substring(.,3,1) * 1 + substring(.,4,1) * 3) + (substring(.,5,1) * 1
> + substring(.,6,1) * 3) + (substring(.,7,1) * 1 + substring(.,8,1) *
> 3) + (substring(.,9,1) * 1 + substring(.,10,1) * 3) +
> (substring(.,11,1) * 1 + substring(.,12,1) * 3)),1) != 0">
> there is an improperly formatted EAN number.
> </sch:report>
>
> don't worry, verbosity isn't a concern in XML.  :)
>
> The same principals can be used to implement a great number of
> algorithms where the boundaries of the problem are know, as in this
> case I know that this sequence is 13 characters in length, not less
> nor more.
>
> Actually because of the way schematrons assert works one can do checks
> on sequences where the possible upper bound is known but not if the
> upper bound is actually reached.
>
> I did a proof of this recently (generated the code of course, it took
> 86 assertions to implement the check), the requirement was that for a
> text string the space between each linefeed was no longer than 37
> characters, and there could not be more than 45 linefeeds.
>
> The generated assertions were of course that the string-length of the
> string between line feed 1 and 2 was less than 38.
> the string-length of the string between line feed 2 and 3 was less
> than 38 and so forth.
>
> If there were only two line feeds the other assertions did not return
> false due to wording.
>
> It took 86 assertions because I split on if the ending line had to end
> with a line feed. Unfortunately my laptop burnt out (nothing to do
> with this example) and I hadn't backed it up because it was a sort of
> a fun experiment. Not for actual use.
>
> This was in Schematron 1.5 not Iso, it would be a lot easier to write
> this stuff in ISO. Of course others out there could probably optimize
> the code, but it has been checking EAN numbers for a year and a half
> now and nobody has submitted an error yet. (fingers crossed)
>
> Cheers,
> Bryan Rasmussen
>
>
>
>
>
> On 1/22/07, Costello, Roger L. <costello@m...> wrote:
> > Hi Folks,
> >
> > I am putting together a list of ways that Schematron is being used.  I
> > seek your help in ensuring that the list is complete. (I will post the
> > final list)
> >
> > Let me give an example to show what I mean by "ways that Schematron is
> > being used".
> >
> > Consider this simple XML instance document:
> >
> > <?xml version="1.0"?>
> > <Document>
> >      <Classification>unclassified</Classification>
> >      <Para>
> >           Lorem ipsum dolor sit amet,
> >           laoreet ac convallis dictumst
> >      </Para>
> >      <Classification>unclassified</Classification>
> > </Document>
> >
> > Schematron can be used to specify, "The Classification value at the top
> > and bottom of the document must match; the Para element must not
> > contain any restricted keywords."
> >
> > Thus, we see Schematron being used to express these two types of data
> > constraints:
> >
> > 1. Co-constraints: in the example the co-constraint is between the two
> > Classification values; namely, the two values must be identical.  In
> > general, co-constraints are constraints that exist between data
> > (element-to-element co-constraints, element-to-attribute,
> > attribute-attribute).  The co-constraints may be "within" an XML
> > document, or "across" XML documents.
> >
> > Schematron is very well-suited to expressing co-constraints.
> >
> > 2. Existence: in the example the existence constraint is that the Para
> > element must not contain any restricted keywords.  The keywords may be
> > obtained dynamically from another file. In general, existence
> > constraints are constraints on the presence or absence of data.  The
> > existence constraints may apply over the entire document, or to just
> > portions of the document.
> >
> > Schematron is very well-suited to expressing existence constraints.
> >
> > Categories of Schematron Usage
> >
> > Here are the ways that Schematron is being used today:
> >
> > 1. Co-constraint checking
> > 2. Existence checking
> >
> > Are you using Schematron in ways not represented by these two
> > categories?  I am particularly interested in identifying ways
> > Schematron is being used which cannot be expressed by other schema
> > languages - XML Schemas, Relax NG.
> >
> > /Roger
> >
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>

• References:
  • Schematron: Categories of Usage?
    • From: "Costello, Roger L." <costello@m...>
  • Re: Schematron: Categories of Usage?
    • From: "bryan rasmussen" <rasmussen.bryan@g...>