shell-command-on-region and coding

[Lennart Borgman]

I have a problem which I find a bit hard to describe in a short way. The 
problem is in tidy.el (which I have rewritten a bit) and I see this 
problem on w32.

In tidy.el there is a line

     (shell-command-on-region fstart end command temp-buffer nil)


The buffer in which this is run has buffer-file-coding-system 
iso-latin-1-unix. Before the command above coding-system-for-write is 
set to iso-latin-1-unix.

Tidy get the information that the coding system is "latin1". Still on 
all Swedish characters (latin 1) I get the error

    Warning: discarding invalid character code 129

from tidy. This is not the character value of the Swedish characters. 
Using describe-char I get something like this for one of those characters:

>>>>>>>>>>>>>>>>>>>>>>>>>
 character: å (2277, #o4345, #x8e5, U+00E5)
   charset: latin-iso8859-1 (Right-Hand Part of Latin Alphabet 1 
(ISO/IEC 8859-1): ISO-IR-100.)
code point: #x65
    syntax: w     which means: word
  category: l:Latin
buffer code: #x81 #xE5
 file code: #xE5 (encoded by coding system iso-latin-1-unix)
   display: by this font (glyph code)
    -outline-Courier 
New-normal-r-normal-normal-13-97-96-96-c-*-iso8859-1 (#xE5)

There are text properties here:
 face                 nxml-text-face
 fontified            t
<<<<<<<<<<<<<<<<<<<

Can someone give me a hint on what is happening here? Is there some 
other variable that should be set before shell-command-on-region?