HDM File – What is .hdm file and how to open it?
HDM File Extension
HDML File – file format by Openwave
HDM (HDML File) is a file extension used for High Definition Markup Language (HDML) files developed by Openwave. HDML is a markup language that is used to create web pages for mobile devices and other devices with limited capabilities.
What is an HDM File?
An HDM file, or Handheld Device Markup Language (HDML) file, is a document format used for creating web pages optimized for handheld devices with limited display capabilities. Originally developed by Openwave, HDM files enable basic web browsing on early mobile phones and PDAs by incorporating elements like hyperlinks, images, and text within a lightweight, simplified syntax akin to HTML.
History and Purpose of HDM Files
HDM files played a crucial role during the early days of mobile internet, facilitating web access on feature phones and PDAs before the advent of smartphones. They are especially noted for their utility in delivering content suited to the limited processing power and screen size of early mobile devices. However, with the evolution of mobile technology and the introduction of advanced browsers, the use of HDM files has significantly declined.
How to Open an HDM File
Opening HDM files can be challenging due to the obsolescence of the HDML format. However, they can still be accessed using a few methods:
- Legacy Web Browsers: Some older web browsers may still support HDML files. Browsers like early versions of Internet Explorer Mobile or custom applications designed for legacy support can open these files.
- HDML Viewers: Dedicated HDML viewer applications are designed to open and interact with HDM files by emulating older mobile device environments.
Current Relevance and Usage
While HDM files are largely obsolete in modern web design, understanding their structure and functionality provides valuable insights into the history of mobile web development. Today, responsive design techniques have replaced the need for device-specific markup languages like HDML.
HDM File Format Details
The HDM file format consists of HDML tags that allow content to be formatted for viewing on handheld devices. These files were commonly transferred using the Handheld Device Transport Protocol (HDTP) rather than HTTP, which is used for contemporary HTML pages.
Key Elements of HDML
| Element | Description |
|---|---|
| Cards | The fundamental unit of HDML, displaying interactive content blocks. |
| Decks | Similar to HTML pages, decks are collections of cards, identified by URLs and cached by the browser. |
| Actions | Interactive elements like PREV, SOFT1-SOFT8, and HELP that facilitate user navigation and interaction. |
| Activities | Groups of related cards that perform logical functions across one or more decks. |
| History-based Navigation | Maintains a history of cards accessed by the user, allowing for easy navigation back through previously viewed content. |