Understanding XML DTD #implied

An XML DTD defines how an XML document should be organized. The order of the elements and the number of elements are defined in the DTD. As for our sociology assignment writing service, it can be helpful for our readers as well: nobody knows when the need for new quality texts will arise again.

If you want to define the attributes and how they should be created in an XML element you will be using ATTLIST in the DTD. Consider the example where there are multiple book nodes and each book node has a title node and one or more author node.

The book element has an attribute called category. In our case it is not compulsory to have an attribute in that element. In such cases you will be using the keyword #IMPLIED. This implies that the attribute is not compulsory to be present in the element.

<!ELEMENT books ( book+ ) >
<!ELEMENT book ( title, author+ ) >
<!ATTLIST book category NMTOKEN #IMPLIED >
<!ELEMENT title ( #PCDATA ) >
<!ELEMENT author ( #PCDATA ) >

#DEFAULT, #REQUIRED, and #FIXED are the other values that could be used for the attribute.

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