IETF RFC 5491 PDF

The Presence Information Data Format Location Object (PIDF-LO) specification provides a flexible and versatile means to represent location information. There are, however, circumstances that arise when information needs to be constrained in how it is represented. In these circumstances, the range of options that need to be implemented are reduced. There is growing interest in being able to use location information contained in a PIDF-LO for routing applications. To allow successful interoperability between applications, location information needs to be normative and more tightly constrained than is currently specified in RFC 4119 (PIDFLO). This document makes recommendations on how to constrain, represent, and interpret locations in a PIDF-LO. It further recommends a subset of Geography Markup Language (GML) 3.1.1 that is mandatory to implement by applications involved in location-based routing.