Here are a few of the languages, styles, and protocols you'll need to familiarize yourself with if you want to design sites that can be handled by tomorrow's handheld devices.
Now in use, the Wireless Application Protocol delivers content to wireless devices like pagers and cell phones.
Also in use, the Wireless Markup Language is to WAP as HTML is to HTTP. WML works in tandem with WAP to help deliver content to wireless applications.
The Extensible Hypertext Markup Language standard is the bridge between HTML and XHTML, allowing Web pages to be backward compatible but positioning them to integrate with XML and other related technologies. Part of the rationale for XHTML is to position Web content for easy modification and access by alternative devices.
Most of you know this onethe Extensible Markup Language. XML allows support for a very wide range of data types, and therefore is attractive to developers working with alternative languages and protocols, including WAP.
Extensible Style Language/Extensible Style Language Transformations embody a write once, display anywhere concept. Developers using transformations will create a style sheet that basically says, "If this device requests the page, deliver it using this style." These technologies are in the "working draft" stage.
Composite Capability/Preference Profile is a framework by which user preferences and device profiles can be delivered by a user agent to a server. The server then returns custom content based on the information received. This protocol extension is a work in progress.