.HDML File Extension
File TypeHandheld Device Markup Language File
What is an HDML file?
Web page created for mobile devices using the Handheld Device Markup Language (HDML); an extension of the SGML language, which is used for creating .SGML files; designed to be displayed on smartphones and other portable electronic devices.
HDML files can be viewed with compatible devices using the Openwave UP.Browser. They can be edited on a computer with a text editor, but are not supported by standard Web browsers.
HDML was introduced by Unwired Planet (now Openwave) in 1996. Around 1999, HDML was replaced by the Wireless Markup Language (.WML), which was influenced by HDML.