Try It Yourself - SyntaxStudy Editor

HTML / CSS / JS

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE library [

<!ELEMENT library (book+)>

<!ELEMENT book    (title, author+, year, price?)>
    <!ELEMENT title   (#PCDATA)>
    <!ELEMENT author  (#PCDATA)>
    <!ELEMENT year    (#PCDATA)>
    <!ELEMENT price   (#PCDATA)>

<!ATTLIST book
        id        ID                        #REQUIRED
        category  (fiction|non-fiction|reference) #REQUIRED
        available (true|false)              "true"
    >

]>
<library>
    <book id="b001" category="non-fiction" available="true">
        <title>XML in a Nutshell</title>
        <author>Elliotte Rusty Harold</author>
        <author>W. Scott Means</author>
        <year>2004</year>
        <price>39.99</price>
    </book>
    <book id="b002" category="reference">
        <title>XML Schema</title>
        <author>Eric van der Vlist</author>
        <year>2002</year>
    </book>
</library>