well formed XML DTD

Question

I ran my XML/DTD through w3schools validator it tells me it has allot of errors, what am I doing wrong? I will admit it's been a few years since I used XML

<?xml version="1.0" encoding="iso-8859-1" standalone="yes"?>
<!DOCTYPE WEBDESIGNTOPICS [
<!ELEMENT WEBDESIGNTOPICS (topic+,topicname+,description+,provided)>
<!ELEMENT topic (#PCDATA)>
<!ELEMENT topicname (#PCDATA)>
<!ELEMENT description (#PCDATA)>
<!ELEMENT provided (#PCDATA)>
]>
<WEBDESIGNTOPICS>
<topic>
    <topicname>HTML5</topicname>
    <description>HAMILTON</description>
    <provided>SALESMAN</provided>

</topic>
<topic>
    <topicname>CSS/CSS3</topicname>
    <description>SMITH</description>
    <provided>CLEANER</provided>

</topic>
<topic>
    <topicname>PHP</topicname>
    <description>JONES</description>
    <provided>MANAGER</provided>
</topic>
<topic>
    <topicname>JavaScript</topicname>
    <description>JONES</description>
    <provided>MANAGER</provided>
</topic>
<topic>
    <topicname>jQuery</topicname>
    <description>JONES</description>
    <provided>MANAGER</provided>
</topic>
</WEBDESIGNTOPICS>

Answer 1

Note that your XML document is well-formed but is not valid. You can read about the difference between well-formed and invalid here.

To make your XML be valid:

1. Change the content model of WEBDESIGNTOPICS to reflect the fact that it's clearly just a list of topics:

    <!ELEMENT WEBDESIGNTOPICS (topic+)>
   

2. Change the content model of topic to reflect that it can consist of a topicname, description, and provided element or elements. You have to decide on the requiredness and cardinality as the sample XML cannot indicate generality itself:

   <!ELEMENT topic (topicname,description,provided)>
   

Altogether then, this updated XML document will be valid:

<?xml version="1.0" encoding="iso-8859-1" standalone="yes"?>
<!DOCTYPE WEBDESIGNTOPICS [
<!ELEMENT WEBDESIGNTOPICS (topic+)>
<!ELEMENT topic (topicname,description,provided)>
<!ELEMENT topicname (#PCDATA)>
<!ELEMENT description (#PCDATA)>
<!ELEMENT provided (#PCDATA)>
]>
<WEBDESIGNTOPICS>
    <topic>
        <topicname>HTML5</topicname>
        <description>HAMILTON</description>
        <provided>SALESMAN</provided>
    </topic>
    <topic>
        <topicname>CSS/CSS3</topicname>
        <description>SMITH</description>
        <provided>CLEANER</provided>
    </topic>
    <topic>
        <topicname>PHP</topicname>
        <description>JONES</description>
        <provided>MANAGER</provided>
    </topic>
    <topic>
        <topicname>JavaScript</topicname>
        <description>JONES</description>
        <provided>MANAGER</provided>
    </topic>
    <topic>
        <topicname>jQuery</topicname>
        <description>JONES</description>
        <provided>MANAGER</provided>
    </topic>
</WEBDESIGNTOPICS>