extending Jeff's letter style

[Barrie Stott]

If I am writing to Joe Bloggs, I would like the header of all but the first
page to have `To: Joe Bloggs' on the left and @PageNum centred.

I'll not reproduce here my version of Jeff's file since, for a day and a
half, it's been constantly changing as I tried to solve this problem. The only
fixed change is that his parameter @To has become two, as below, so that I can
extract the name from name+address.

    def @Letter
      named @ToName {}
      named @ToAddress {}

Essentially, I think I need to have the effect of the following towards the
end of my setup file (There would be @OddTop and @PageNum in there as well but
that's detail.):

    @Use { @DocumentSetup
             @EvenTop { To: @ToName }
         }

The problems I have are these:

1. @EvenTop is in scope within @DocumentSetup but @ToName is not. I have tried
so many variations to get something in scope that I'm beginning to think that
it cannot be done. Hence the question: Is there a way for me to get @ToName
in scope for @DocumentSetup?

2. Even supposing that I could crack the previous problem, at the time
@EvenTop is set by the above, @ToName has an empty value rather than `Joe
Bloggs' so I wouldn't get what I wanted anyway.

Any help would be much aprreciated.

Barrie.