[texhax] problem with \mark, or with me?

[Paul Isambert]

Marks are made available in the output routine, that's why your document 
doesn't work. When you say:

mark a\mark{$\alpha$}

-\topmark-
-\firstmark-
-\botmark-

\top-, \first- and \botmark are still empty because they are defined at 
output time, so what is printed here is their values at the last output 
(hence the one-page delay).

Try the following dummy routine:

\output{
  \shipout\vbox{
    \unvbox255
    \hbox{Topmark: \topmark}
    \hbox{Firstmark: \firstmark}
    \hbox{Botmark: \botmark}}
  }

and you'll see that whereas your test is ill-defined, at output time 
marks are set to the correct values.

Paul


Stan a écrit :
> After having difficulty creating some macros involving \mark, I 
> returned to the basics and set up the situation described on page 258 
> of the TeXbook, and typeset it using Plain TeX.  Unfortunately, my 
> results don't match those described in the book.  Everything in the 
> file I produced is shifted by a page, so for example, the state of 
> \topmark etc. that the TeXbook says should be on page 3, I have on 
> page 4.  Is this just some careless mistake on my part?  Here is the 
> text from my file:
>
>
> first page
>
> -\topmark-
> -\firstmark-
> -\botmark-
>
> \vfill\eject
>
> second page
>
> mark a\mark{$\alpha$}
>
> -\topmark-
> -\firstmark-
> -\botmark-
>
> \vfill\eject
>
> third page
>
> -\topmark-
> -\firstmark-
> -\botmark-
>
> \vfill\eject
>
> fourth page
>
> mark b\mark{$\beta$}
>
> mark c\mark{$\gamma$}
>
> -\topmark-
> -\firstmark-
> -\botmark-
>
> \vfill\eject
>
> fifth page
>
> mark d\mark{$\delta$}
>
> -\topmark-
> -\firstmark-
> -\botmark-
>
> \vfill\eject
>
> sixth page
>
> -\topmark-
> -\firstmark-
> -\botmark-
>
> \vfill\eject
>
> seventh page
>
> -\topmark-
> -\firstmark-
> -\botmark-
>
> \bye
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