List of possible choices in a DTD

[Ingo Macherius]

> From:          "Thorsten Kitz" <thoki at csi.com>
> Subject:       List of possible choices in a DTD

> I have a really simple problem: I like to define a choice list in a
> DTD, eg for element <Weekdays> a list of possible values like
> "Monday", "Tuesday", etc.

So the name of the weekday is data content, not structural 
information. Consider how this is done with HTML 4:

<!ELEMENT SELECT - - (OPTION)+ -- option selector -->
<!ELEMENT OPTION - O (#PCDATA) -- selectable choice -->

so a typical instance would be

 <select>
  <option>Monday</option>
  [...]
  <option>Sunday</option>
 </select>

Display of the list is a processing semantic, that can't be expressed
in the DTD. It's up to your application to make this a choice list,
eiher like a pulldown menu, a item list, etc.

Of course you could use specific names for your list, like
 <week>
  <day>Monday</day>
  [...]
  <day>Sunday</day>
 </week>

or even
 <week>
  <monday>[...]</monday> 
  <!-- or <monday/> if no content is necessary  -->
  [...]
  <sunday>[...]</sunday>
 </week>

but the more tags you have, the more compicated your stylesheets etc.
become. To me names of days are data, not structure. Anyway, the last 
example is different, as it may contain information *about* the 
weekdays, e.g a hourly schedule.

Alternatively, weekdays could be attributes

	<week>
 		<day name="monday">[...]</day>
		[..]
		<day name="sunday">[...]</day>
	</week>

Choice is up to you, but nowhere I can see a need for entities.

	++im

BTW: XSL does not say anything about forms ! Should there be a 
standard forms set, just like there are CALS tables and MathML ?
--
Ingo Macherius // L'Aigler Platz 4 // D-38678 Clausthal-Zellerfeld
mailto:Ingo.Macherius at tu-clausthal.de    http://www.tu-clausthal.de/~inim/
Information!=Knowledge!=Wisdom!=Truth!=Beauty!=Love!=Music==BEST (Frank Zappa)

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