Re: Footer trap in a A4 PDF

[Tadziu Hoffmann]

> How should I proceed to achieve precise margin sizes?

There's two things to consider here.  One: the trap is sprung
when a line is output that reaches OR SWEEPS PAST the trap
position.  If you set your trap at -2 cm, then an output
line may nevertheless still intrude into the bottom margin
of 2 cm.  Unless you have over-tall lines, this will usually
be not more than the baseline distance of the running text.
If you want to keep the bottom 2 cm of the page free of text,
then it may be a good idea to set the trap at -2c-1v.

Two: if your footer macro just outputs the footer line without
doing anything else, then the position of the footer line WILL
DEPEND ON where the last line of text had been output, and thus
may vary from page to page.  To keep the footer line always
in the same position, have the footer macro space absolutely
to the desired position before outputting the footer line.

Also, if the footer (and header) lines should be output in a
different font, size, or color, it is best to reserve a separate
environment for the headers and footers, in order to minimize
interactions with the running text.  E.g., you might use

  environment 0: normal running text
  environment 1: headers and footers
  environment 2: footnotes

I have attached a demonstration file you can use for experimenting.
(I have used 3 cm margins for this.  Coloring the margins with XX
(for debugging purposes) only works with the PS device; you can
safely remove this.)

footer.ro
Description: Text document

footer.pdf
Description: Adobe PDF document