hi, Wolfgang Schuster and Sietse Brouwer
   Thank you for your patience!
   I got it !

BEST REGARDS
PengCZ


2013/1/7 Wolfgang Schuster <wolfgang.schuster@gmail.com>

Am 06.01.2013 um 15:10 schrieb Sietse Brouwer <sbbrouwer@gmail.com>:

>>> but the rightmarginwidth = 3.7569cm, not 0.1cm, I do not know why?
>>> what should I do to widen the texwidth?
>>
>> http://www.ntg.nl/pipermail/ntg-context/2012/064650.html
>
> In which Wolfgang wrote:
>> The horizontal dimensions are determined by the three values
>>
>> - backspace (distance from the left/inner margin)
>> - cutspace (distance from the right/outer margin)
>> - width (width of the textblock)
>>
>> Normally you need only two values because when you set
>> backspace + width the cutspace is > calculated and when
>> you set backspace + cutspace you can write width=middle
>> and the width of the text block will be calculated.
>
> Which is a good explanation, and he explains how vertical dimensions
> work, too. Allow me to add this e-mail to answer another question you
> will probably have: "What about the marginwidth, margindistance,
> edgewidth, and edgedistance? Those are also horizontal values!"
>
> A good question. The answer is that ‘margin’ means two things:
> 1. the space between the edge of the textblock and the boundary of the paper
> 2. a typesetting area inside that space, in which marginal material is typeset.
>
> Inside \setuplayout, margin has the second meaning: marginwidth is the
> width of the margin, and margindistance the distance between the text
> area and the margin area.
>
> There are also the ‘edges’: these are typesetting areas outside the
> margin areas. Some uses I can think of: colouring the edge of the page
> in a guidebook with sections; placing informative marks in general;
> printing a sort of vertical header/footer; etc.
>
> This is not a bad reference:
> http://wiki.contextgarden.net/Layout


I wrote a short seven page example where you can see both margins
don’t influence the layout because they’re just put on the sides like
attachments.

\setuppapersize[A4][A3]

\setuplayout
  [location=middle,
   header=0pt,
   footer=0pt]

\setuppagenumbering[location=]

\definefont[BigFont][Mono*none sa 4]

\starttext

\showframe[page]
\centerbox{\BigFont PAGE}\page

\setuplayout
  [backspace=2cm,
   cutspace=2cm,
   width=middle,
   topspace=2cm,
   bottomspace=2cm,
   height=middle]

\showframe[text]
\centerbox{\BigFont TEXTBLOCK}\page

\setuplayout
  [header=2cm,
   headerdistance=1cm,
   footer=2cm,
   footerdistance=1cm]

\showframe[header,footer]
\centerbox{\BigFont HEADER/FOOTER}\page

\setuplayout
  [leftmargin=2cm,
   leftmargindistance=1cm]

\showframe[leftmargin]
\centerbox{\BigFont LEFTMARGIN}\page

\setuplayout
  [leftedge=2cm,
   leftedgedistance=1cm]

\showframe[leftedge]
\centerbox{\BigFont LEFTEDGE}\page

\setuplayout
  [rightmargin=2cm,
   rightmargindistance=1cm]

\showframe[rightmargin]
\centerbox{\BigFont RIGHTMARGIN}\page

\setuplayout
  [rightedge=2cm,
   rightedgedistance=1cm]

\showframe[rightedge]
\centerbox{\BigFont RIGHTEDGE}\page

\stoptext

Wolfgang
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________