XCONCUR is an experimental markup language with the major goal to provide a convenient method to express concurrent hierarchies in an XML-like fashion. XCONCUR-CL is a validation component in XCONCUR and allows cross-layer validation.
textMD is a XML Schema maintained by the Library of Congress that details technical metadata for text-based digital objects. It allows for detailing properties such as encoding information (quality, platform, software, agent), character information (character set and size, byte order and size, line terminators), languages, fonts, markup information, processing and textual notes, technical requirements for printing and viewing, and page ordering and sequencing.