[Python-Dev] Edits to Metadata 1.2 to add extras (optional dependencies)

[Stephen J. Turnbull]

Petri Lehtinen writes:
 > Daniel Holth wrote:
 > > I don't know of a tool that doesn't reliably ignore extra fields, but
 > > I will put you down as being in favor of an X- fields paragraph:
 > > 
 > > Extensions (X- Fields)
 > > ::::::::::::::::::::::
 > > 
 > > Metadata files can contain fields that are not part of
 > > the specification, called *extensions*. These fields start with
 > > with `X-`.
 > 
 > See RFC 6648 for why such X-fields may not be a good idea:
 > 
 >     http://tools.ietf.org/html/rfc6648

But note that the RFC also says that the preferred solution to the
problem that X-fields are intended to solve is an easily accessible
name registry and a simple registration procedure.  If Martin's "be
prepared for a ten-year period to acceptance" is serious, what should
be done about such a registry?