Mobile Markup Languages

Mobile devices, because of their small screens, have required a rethinking about the way information, particularly graphic information, is displayed on the small screens. The first tendency, in early mobile markup language implementations, was to leave out the graphics, or only include very small graphics. There are now more advanced solutions that allow full4 Web pages to scale down for viewing on a small screen. Here is an overview of the markup languages used to create Web pages viewable on small screens.

XHTML (WAP 2.0)

XHTML is the successor to HTML and technically the reformulation of HTML 4.0 within the strict formatting of XML pages. The reason for this reformulation of HTML is due to the number of devices now used to access the Internet. HTML is a “loosey-goosey” markup language that requires a fairly heavy-duty parser -a special translation program - to correctly display HTML. Mobile devices just don’t have the horsepower or resources to properly parse HTML, so switching to the very strict format of XML reduces the overhead necessary to properly display HTML.

WAP 2.0 is the latest version of the Wireless Application Protocol, the technology used by many mobile devices to provide Internet access. WAP acts as a gateway for XHTML content onto the mobile devices. Someday, WAP will be replaced by WIP (Wireless Internet Protocol), considered to be a true Internet protocol.

The official Web site for XHTML is www.w3.org/TR/xhtml1/.

WML (WAP 1.2)

Wireless Markup Language (WML) is an XML-based language used for displaying mobile Web pages. It is considered an older technology and is largely being replaced by XHTML. WML was the first language to be understood by wireless “micro-browsers,” which were created to conform to the WML 1.1 DTD (Document Type Definition).

The official Web site for WML is www.wapforum.com.

cHTML (iMode)

Japanese-based NTT DoCoMo decided to create a competing technology to WAP called i-Mode. I-Mode, or commonly iMode, uses cHTML, compact HTML, as its markup language to create Web pages for small mobile devices. cHTML is a significantly smaller subset of HTML, thus cutting down on the need to parse the full version of HTML tags. cHTML does not support common HTML features such as JPG image support, tables, image maps, multiple fonts and font styles, background colors and images, frames, and style sheets. Basically, it supports two colors, usually black and white. While still used largely in Japan, cHTML is being replaced by the more widely used XHTML.

The official Web sites for cHTML (in Japanese) are www.access.co.jp/ and (in English) www.access.co.jp/english/index.html.