In February of 1998, the World Wide Web Consortium (W3C) formally recommended the Extensible Markup Language (XML) as an industry-wide standard. XML is a data format for structured document interchange derived from the Standard Generalized Markup Language (SGML). XML documents are ASCII files containing both text as well as tags identifying structures within that text. However, unlike Hypertext Markup Language (HTML), XML allows custom definition of tags and attributes. XML itself is not a single mark-up language: it's a metalanguage that lets you design your own mark-up language. XML is designed in accordance with SGML, the international standard metalanguage for mark-up languages.
Under the sponsorship of the Space and Naval Warfare Systems Command (PMW-185), Navy developers have designed and implemented an application of XML, the Weather Observation Markup Format (OMF), to describe particular types of weather data. Initially, data types of interest to the aviation forecasting community were selected for implementation. These include METAR and SPECI aviation routine and selected special weather reports, Terminal Aerodrome Forecasts (TAFs),and Significant Meteorological Information warnings (SIGMETS). OMF provides a means to distribute several data types, received in a variety of formats, within a single, structured format. While fully preserving the text of the original report, OMF annotates it with additional, derived and meta- data, such as station names, ids, position, cloud ceiling, relative humidity, wind chill, etc. In addition to structure and extensibility, XML documents can be validated, ensuring that each tag set is properly defined.
The Joint METOC Viewer (JMV), an application used by Navy forecasters to display meteorological data, is the first application to incorporate OMF. Because of the availability Java XML parsers, Web-based uses of OMF in Java applets is also underway. The XML solution is system-independent, vendor-independent, and proven by over a decade of SGML implementation experience. XML is destined to play a significant role in the future of data exchange on the Internet and with OMF, the Navy’s meteorological community is preparing to take full advantage of its benefits.