od -t a to warn for non-ASCII

[Ed Avis]

If you run 'od -t a' then the high bit is silently stripped out of the 
input.  This can cause a bit of confusion (especially when dealing 
with char 160 (non-breaking space) in ISO-8859-1 which strips down to 
a regular space...)

I suggest that when 'od -t a' encounters the first high-bit-set 
character in the input it should print a warning that the bit is being 
ignored, and that if you have input files that might not be pure ASCII 
then 'od -t c' might be a better choice.  This warning could be 
disabled when POSIXLY_CORRECT is set.

If you don't want to do that, please update the help text and info 
documentation to make it clear that the 'a' format maps high-bit-set 
characters onto the same output as ASCII, and so probably isn't what 
you want if you are trying to see what characters a byte stream 
contains.

--
Ed Avis <address@hidden>