[DCMI] Dublin Core Metadata Initiative. Dublin Core Metadata Element Set, Version 1.1. Dublin Core Metadata Initiative, January 2008, http://dublincore.org/documents/dces/. Now also an ISO standard: ISO 15836:2009.

[NVDL] ISO. Namespace-based Validation Dispatching Language (NVDL). International Organization for Standardization, ISO/IEC 19757-4, 1 June 2006, http://www.nvdl.org/.

[Unicode] Julie D Allen, et al., ed. The Unicode Standard Version 5.2.0. The Unicode Consortium, December 2009, http://www.unicode.org/standard/standard.html.