DTD won't parse, don't understand the error messages

[Simon Brooke]

I have (obviously) an error in my DTD. Different parsers give me
different error messages, but none of them help me understand the problem
or how to fix it.

sgmls says 'onsgmls:<URL>http://bowyer.journeyman.cc/adl/stable/adl/
schemas/adl-1.4.dtd:483:27:E: "canonical" is not a reserved name'

Xerces says 'http://bowyer.journeyman.cc/adl/stable/adl/schemas/
adl-1.4.dtd:483:28arse Error: the attribute type is required in the
declaration of the attribute "sequence" for the element "order".

What's actually there at 483 is:

<!ELEMENT order (documentation?)>
<!ATTLIST order
property CDATA #REQUIRED
sequence %Sequences; #IMPLIED>

where Sequences is defined at line 174 as

<!-- sequences for orderings of lists - see entity 'order'
canonical: Whatever the normal canonical ordering for this
datatype is -
typically alpha-numeric, except for dates, etc.
reverse-canonical: The reverse of the above

possibly there should be some further values but I have no idea what
these are
-->
<!ENTITY % Sequences "canonical|reverse-canonical">

Ideally I'd like not only to know how to fix it, but to understand why
it's wrong in order that I don't make the same mistake again.

Thanks!

 

[Stanimir Stamenkov]

20 Jun 2010 14:53:22 GMT, /Simon Brooke/:

Xerces says 'http://bowyer.journeyman.cc/adl/stable/adl/schemas/
adl-1.4.dtd:483:28arse Error: the attribute type is required in the
declaration of the attribute "sequence" for the element "order".

What's actually there at 483 is:

<!ELEMENT order (documentation?)>
<!ATTLIST order
property CDATA #REQUIRED
sequence %Sequences; #IMPLIED>

where Sequences is defined at line 174 as

<!ENTITY % Sequences "canonical|reverse-canonical">

Ideally I'd like not only to know how to fix it, but to understand why
it's wrong in order that I don't make the same mistake again.

Obviously you're missing the parentheses around the enumeration [1].
You could either put them in the ATTLIST declaration:

<!ATTLIST order
property CDATA #REQUIRED
sequence (%Sequences #IMPLIED>

or in the ENTITY one:

<!ENTITY % Sequences "(canonical|reverse-canonical)">

depending on how you plan to use the %Sequences; entity.

[1] http://www.w3.org/TR/xml/#dt-enumerated