- RFC 6155 - Use of Device Identity in HTTP-Enabled Location Delivery (HELD), accessible [here](https://tools.ietf.org/html/rfc6155)
- RFC 3863 - Presence Information Data Format (PIDF), accessible [here](https://tools.ietf.org/html/rfc3863)
- RFC 4119 - A Presence-based GEOPRIV Location Object Format, accessible [here](https://tools.ietf.org/html/rfc4119)
- RFC 5139 - Revised Civic Location Format for Presence Information Data Format Location Object (PIDF-LO), accessible [here](https://tools.ietf.org/html/rfc5139)
- RFC 7459 - Representation of Uncertainty and Confidence in the Presence Information Data Format Location Object (PIDF-LO), accessible [here](https://tools.ietf.org/html/rfc7459)
NOTE All draft can be found in the 'IETF XML Registry', accessible [here](https://www.iana.org/assignments/xml-registry/xml-registry.xhtml)