Extensible Resource Descriptors
We refer to the definition of XRD's by Oasis here: http://docs.oasis-open.org/xri/xrd/v1.0/xrd-1.0.html
This library implements the XML format as defined by Oases, as well as the JSON format as defined in Appendix A of RFC 6415: https://tools.ietf.org/html/rfc6415#appendix-A.
This document format is used by f.e. WebFinger and Web Host Metadata.