The Uniform Resource Identifier (URI) protocol element and generic syntax is
defined by [RFC3986]. Each URI begins with a scheme name, as defined by Section 3.1
of RFC 3986, that refers to a specification for identifiers within that scheme. The
URI syntax provides a federated and extensible naming system, where each scheme’s
specification can further restrict the syntax and define the semantics of
identifiers using that scheme. This document provides updated guidelines for the
definition of new schemes, for consideration by those who are defining,
registering, or evaluating those definitions.