Re: [xml-dev] How to avoid the sequens of child elements in DTD, yet keep the cardinality?

[Francis Norton <francis@redrice.com>]

Albena,

You can't as far as I know implement this in DTDs. However it is fairly
simple to implement in Schematron, with a grand total of four
assertions.

For more details of schematron see
http://www.ascc.net/xml/resource/schematron/schematron.html

Francis.

<sch:schema xmlns:sch="http://www.ascc.net/xml/schematron";>
  <sch:title>movies</sch:title>
  <sch:pattern name="Header">
    <sch:rule context="Header">
      <sch:assert test="Identification"
        >The Header must have one or more Identification
elements.</sch:assert>
      <sch:assert test="Category"
        >The Header must have one or more Category
elements.</sch:assert>
    </sch:rule>
    <sch:rule context="Header/*">
      <sch:assert test="self::Identification or self::Category or
self::Weight or self::Keyword"
        >Children of Header must be Identification, Category, Weight or
Keyword, but this was a <name/>.</sch:assert>
      <sch:assert test="not(preceding::*[1][name() !=
name(current())][preceding::*[name() =  name(current())]])"
        >This <name/> was not grouped with the other
<name/>s.</sch:assert>
    </sch:rule>
  </sch:pattern>
</sch:schema>

---
C:\xml\schematron>sch-basic t-good.xml t
movies

C:\xml\schematron>sch-basic t-bad.xml t
movies
In pattern not(preceding::*[1][name() !=
name(current())][preceding::*[name() = name(current())]]):
   This Keyword was not grouped with the other Keyword s.
---

Hope this helps -

Francis.


Albena Georgieva wrote:
> 
> Hi there,
> 
> I am creating a DTD document and I have difficulty to express
> that the element type Header:
> 
> 1. must have one and only one child element of type Indentification
> 2. Can have [0 ... 1] Weight children elements
> 3. Must have at least one Category child element
> 4. Can have [0 ... n] Keywords
> 5. The order of the different children is not important
> 6. If there are several children of the same type, then they should be
> following each other
> 
> Good example:
> <Header>
>    <Keyword>Navratilova</Keyword>
>    <Keyword>Tennis</Keyword>
>    <Identification id="1111"/>
>    <Category>Sports</Category>
> </Header>
> Another good example:
> <Header>
>    <Category>Sports</Category>
>    <Keyword>Navratilova</Keyword>
>    <Keyword>Tennis</Keyword>
>    <Identification id="1111"/>
>    <Weight priority="3"/>
> 
> </Header>
> 
> Not accepted example
> <Header>
>    <Category>Sports</Category>
>    <Keyword>Navratilova</Keyword>
>    <Identification id="1111"/>
>    <Keyword>Tennis</Keyword>
>    <Weight priority="3"/>
> </Header>
> 
> I tried as follows:
> 
> <!ELEMENT header (Identification| Weight? | Category+ | Keyword* )+>
> But then also this example becomes valid which is not what I am aiming to:
> 
> <Header>
>    <Category>Sports</Category>
>    <Keyword>Navratilova</Keyword>
>    <Keyword>Tennis</Keyword>
>    <Identification id="1111"/>
>    <Weight priority="3"/>
>    <Category>Sports</Category>
>    <Identification id="2222"/>
> 
> </Header>
> 
> And if I say so:
> <!ELEMENT header (Identification, Weight?, Category+, Keyword* )>
> 
> It is better, but then we have to comply to the sequence of the children,
> which is what I want to avoid ...
> Any ideas, help please?
> 
> I wish you all a very nice day!
> Greeting,
> Albena Georgieva
> 
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