(
Handheld
Device
Markup
Language) An earlier version of HTML designed to enable wireless pagers and cellphones to access the Web. Developed by Phone.com (later Openwave Systems) before the wireless application protocol (WAP) specification was standardized, most of the features of HDML became a subset of WAP. AT&T Wireless launched the first HDML-based service in 1996. See
WAP and
HTML.