XML stands for eXtensible Markup Language (XML). It is the standard used for World Wide Web (WWW) data exchange. It is well supported by public domain software. The format which will be used for generating the new XML products will be a Digital Weather Markup Language (DWML)-based version of XML. The DWML is used to share weather data. The specifications were written with enough flexibility however to accommodate other environmental science applications. DWML consists of three main parts: a header section containing a description of the product, a temporal definition section, and the forecast data section. For a complete description of DWML see https://www.weather.gov/mdl/XML/Design/MDL_XML_Design.htm.

On inspection, there are similarities between XML and HyperText Markup Language (HTML). However, XML is used to describe the data, whereas HTML is used to describe the format or to display the data.