User Payment Scheme Registration description in charter

I'm concerned with the description of the "User Payment Scheme
Registration" deliverable in the draft charter at:
https://www.w3.org/Payments/IG/wiki/Roadmap/PaymentArchitectureWG
(which has shifted a bit over the past week, during the face-to-face
meeting).

It currently [1] says:
  #  User Payment Scheme Registration: Best practices that should be
  #  followed by the User Agent for the payer to register and
  #  unregister payment schemes and the payment instruments that
  #  implement them. 

Defining only best practices doesn't seem sufficient; I think there
does need to be technical specification work here.  Otherwise it's
not clear to me how the system is open to either multiple browsers
or multiple payment providers.

(I'm not saying that it's clear to me exactly how to describe that
work, though.)

-David

[1] current version URL is:
https://www.w3.org/Payments/IG/wiki/index.php?title=Roadmap/PaymentArchitectureWG&oldid=1995

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
             What I was walling in or walling out,
             And to whom I was like to give offense.
               - Robert Frost, Mending Wall (1914)