The Green Building XML schema, or "gbXML", is a type of XML file that has over 500 types of elements and attributes that allow you to describe all aspects of a building. It was developed to facilitate the transfer of building information stored in CAD-based building information models, enabling interoperability between disparate building design and engineering analysis software tools. Read more about it here.

A sample gbXML file contains a number of containers and its tree structure would look like this:

Solution Deployment Descriptor (SDD) is a standard XML-based schema defining a standardized way to express software characteristics required for lifecycle management in a multi-platform environment.

Unlike a gbXML file, a SDD XML allows for additional terms and descriptions to be included on internal loads and mechanical systems on top of the building geometry schema. SDD XML has been specifically developed for use in energy code compliance. California Title 24 compliance software often utilizes SDD XML making it easy to transfer models for final documentation. Read more about it here.

A file with the .xml file extension is an Extensible Markup Language (XML) file. These are really just plain text files that use custom tags to describe the structure and other features of the document.

XML was created by the World Wide Web Consortium (W3C) to define a syntax for encoding documents that both humans and machines could read. It does this through the use of tags that define the structure of the document, as well as how the document should be stored and transported.