XML.com FAQs > C. Authors of SGML (including writers of HTML: Web page owners)
Question:  C.13 Does XML let me make up my own tags?
Answer:

No, it lets you make up names for your own elements. If you think tags and elements are the same thing you are already in trouble: read the rest of this question carefully.

Before we start this one, Bob DuCharme notes: Don't confuse the term `tag' with the term `element' . They are not interchangeable. An element usually contains two different kinds of tag: a start-tag and an end-tag, with text or more markup between them.

XML lets you decide which elements you want in your document and then indicate your element boundaries using the appropriate start- and end-tags for those elements. Each <!ELEMENT... declaration defines a class of elements that may or may not be used in a document conforming to that DTD. We call this class of elements an `element type' . Just as the HTML DTD includes the H1 and P element types, your document can have color and price element types.

Non-empty elements are made up of a start-tag, the element's content, and an end-tag. <color>red</color> is a complete instance of the color element. <color> is only the start-tag of the element, showing where it begins; it is not the element itself.

Empty elements are a special case that may be represented either as a pair of start- and end-tags with nothing between them (eg <price retail="123"></price>) or as a single empty element start-tag that has a closing slash to tell the parser `don't go looking for an end-tag to match this' (eg <price retail="123"/>). [Bob DuCharme]


This FAQ is from The XML FAQ, maintained by Peter Flynn