Design a DTD

[dvknn]

I am trying to design a DTD. I have a question.

I have 2 fields of which either of them should be present. For example:

X1 and X2 are the field anmes. Atleast one of them or both of them should be present.

How can I indicate that in the DTD design?

Thank You

 

[JeffHoeft]

by field anmes do you mean Elements?

looking for clarification

 

[JeffHoeft]

Here is how I would handle your situation as i understand it:

<?xml version=&quot;1.0&quot; ?>
<!DOCTYPE testXML [
<!ELEMENT testXML (( x1 | x2 ), x1?, x2? )>
<!ELEMENT x1 (#PCDATA) >
<!ELEMENT x2 (#PCDATA) >
]><testXML>
   <x2>some value</x2>
   <x1>some other value</x1>
</testXML>

hope this helps

by the by, you will notice that this will allow x1 and x2 to come in any sequence but only once.

 

[dvknn]

huh?...
OK..This way, either x1 or x2 should be present (that is my requirement. either should be present). but, how can I restrict that x1 and x2 should follow a particular order??


<?xml version=&quot;1.0&quot; ?>
<!DOCTYPE testXML [
<!ELEMENT testXML (x1?, x2?, x3)>
<!ELEMENT x1 (#PCDATA) >
<!ELEMENT x2 (#PCDATA) >

Thanks,

 

[JeffHoeft]

Hello again!

Try this in your xml validator:

<?xml version=&quot;1.0&quot; ?>
<!DOCTYPE testXML [
<!ELEMENT testXML ( x1  | (x1 , x2) | x2 )>
<!ELEMENT x1 (#PCDATA) >
<!ELEMENT x2 (#PCDATA) >
]><testXML>
   <x1>some other value</x1>
   <x2>some value</x2>
</testXML>

depending on how loosly your validator follows the XML specification 1.0 appendix E, this will work.

here is a validator that accepts the definition:

http://msdn.microsoft.com/downloads...amples/internet/xml/xml_validator/default.asp

and here is one that is very picky:

http://www.stg.brown.edu/service/xmlvalid/