An XML document is a text file and consists of two character types: the actual data and the so-called tags or markups. Tags are XML instructions, which describe the division of the document into storage units and its logical structure. The structure itself is saved in a document type definition (DTD).
Tags are always written in pairs in angle brackets. Every start tag always has a corresponding end tag.
XML attributes are used within the tags. An attribute may only occur once within a tag.
XML documents consist of elements. An element is made up of two XML tags and the enclosed text. Blank elements consist of only one tag and always end with a slash (/) before the final bracket.
You can create simple XML documents with a text editor. In the following example, the DTD is specified in square brackets in the XML file directly:
<?xml version="1.0"?>
<!DOCTYPE memberlist
[
<!ELEMENT memberlist (no, name, age)>
<!ELEMENT no (#PCDATA)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT age (#PCDATA)>
]>
<memberlist>
<no>001</no>
<name>Doe, John</name>
<age>27</age>
</memberlist>
If you save this document under the name of your choice with the extension .xml, Internet Explorer can display the document in a structured form.