Interfaces page error

[rpavlik]

https://github.com/OSVR/OSVR-Docs/blob/master/Developing/interfaces.md

Position and orientation are not separate interfaces - they are both part of the tracker interface. This page should be reviewed for accuracy and linked to https://github.com/OSVR/OSVR-Specs-and-Proposals/tree/master/Interface%20Class%20Specifications

And, there is no such thing as a "property" in OSVR (consider it a reserved word, since such a thing may exist in the future). You can query for interface state of a particular type, instead of/in addition to registering a callback, which has a similar effect as what is described.