ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / The next generation of telemetry systems will rely heavily on XML-based standards. Multiple standards are currently being developed and reviewed by the T&E community, including iNET's Metadata Description Language (MDL), the XML-version of IRIG 106, Chapter 9 (TMATS XML), the Instrumentation Hardware Abstraction Language (IHAL), and the Data Display Markup Language (DDML). In this paper, we share design considerations for developing XML-based T&E standards, gained from our experiences in designing IHAL and DDML.