dtd to show alternate sub-nodes?

[engwar]

I'm new to XML and have been given an XML document for which I need to
reverse-engineer a DTD.

There are nodes that have one of two different sets of children. I'm
not sure how to represent this in a DTD. We will have a bunch that
match the first two below, with ChildNode1 and ChildNode2 but then
will have a group that have different child-nodes.

How can I create a dtd to describe this?

Thanks.

<someNode>
<childNode1/>
<childNode2/>
</someNode>

<someNode>
<childNode1/>
<childNode2/>
</someNode>

<someNode>
<childNode3/>
<childNode4/>
</someNode>

 

[=?ISO-8859-1?Q?J=FCrgen_Kahrs?=]

I'm new to XML and have been given an XML document for which I need to
reverse-engineer a DTD.

There are tools for doing this:

http://saxon.sourceforge.net/dtdgen.html
http://home.vrweb.de/~juergen.kahrs/gawk/XML/xmlgawk.html#Generating-a-DTD-from-a-sample-file

 

[Joseph Kesselman]

There are nodes that have one of two different sets of children. I'm
not sure how to represent this in a DTD.

The obvious way would be

( (ChildNode1, ChildNode2) | (ChildNode3, ChildNode4) )

See http://www.w3.org/TR/REC-xml/#sec-element-content