What Is WML?

WML (Wireless Markup Language) is the dominant language in use with wireless devices today. Essentially, WML is a subset of HTML, but has its roots in XML. Those developers with a solid base in XML should have a relatively easy time coding WML.

The current WML standard is 1.3, although many mobile devices in use today support only the WML 1.1 standard. Therefore it's prudent to stay away from 1.3-specific features, unless you know that your target market's devices are 1.3-ready.

There are several key differences between WML and standard HTML, including the following:

WML is highly structured and very particular about syntax. Several current HTML browsers allow for "messy" code such as missing tags and other formatting snafus. Such mistakes are not allowed in WML; the mobile browser will complain and generally won't display the page.

WML is case sensitive. The tags and are treated as different tags, although they accomplish the same purpose (bold text). Therefore, you must be careful to match the case of your opening tags with your closing tags (for example, This is bold will not work as expected).

Many tags have required attributes. Developers accustomed to HTML may be used to including only attributes they need-in some WML tags, you must include a few attributes, even if they are blank or default.

WML pages are structured in "decks" (see the next section), allowing for multiple pages to be defined in each WML file.
WML also has a client-side scripting language, WMLScript, to help automate particular tasks, validate input, and so on. WMLScript is a subset of JavaScript and will be covered in a later article.