xml-dev - Re: Q: Using XML entities for href's - More questions about entities

[Wilf Reedijk <wilfr@mail.bc.rogers.wave.ca>]

When I try to reference an entity within an attribute value, the parser
(I am using msxml) complains.
The message that I am getting is 'Invalid element in context of 
'APP'. Expected [ADDURL,EDITURL] in line 3 and column 18. This
message makes no sense to me.

Here is my XML:
 

<?XML version="1.0"?>
<!DOCTYPE TREE [
<!ENTITY TEST "myapp">
<!ELEMENT TREE (CATEGORY)*>
<!ELEMENT CATEGORY (ADDURL?,EDITURL?,(CATEGORY|APP)*)>
 <!ATTLIST CATEGORY
  name CDATA #REQUIRED>
<!ELEMENT APP (ADDURL?,EDITURL?)>
 <!ATTLIST APP
  name CDATA #REQUIRED
  thing CDATA #IMPLIED>
<!ELEMENT ADDURL (#PCDATA)*>
<!ELEMENT EDITURL (#PCDATA)*>
]>
<TREE>
 <CATEGORY name="mycategory">
 
  <APP name="&TEST;">
   <ADDURL>  someurl </ADDURL>
   <EDITURL> anotherurl </EDITURL>
  </APP>
 </CATEGORY>
</TREE>
 

How do we use entities within attributes?

I find the whole concept of entities to be a bit confusing (internal vs. external; general vs. parameter; parsed vs. unparsed etc.). Is there a site where one could find some good examples describing how the various types of entities are used?
 

Eve L. Maler wrote:

It's legal to reference a parsed entity from an attribute value, and every
XML processor should be able to handle it.  To do this properly, the
reference would have to look like this:

<aTag xml-link="simple" href="&aRef;">content</aTag>

(Using an ENTITY-type attribute wouldn't automatically expand it in place,
and anyway, has to be used exclusively with unparsed entities -- those with
an NDATA notation.)

        Eve