"Introduction The Extensible Markup Language (XML) is a format for structured text that can be used to represent a variety of data in a machine-readable form. The XML syntax used in this standard conforms to the ""Extensible Markup Language (XML) 1.0 (Fifth Edition)""@ and the XML datatypes used in this standard@ indicated by the prefix ""xs:""@ refer to the datatypes defined by ""XML Schema Part 2: Datatypes Second Edition."" This syntax allows data structure definitions@ such as those in Clause 21@ and instances of those definitions to be represented in XML. The syntax is optimized for efficient representation of BACnet data and is sufficiently flexible not to be limited to modeling BACnet data exclusively. Additionally@ the syntax allows for human language descriptions@ range restrictions@ and usage information to be added to the basic data structure definitions."