>> Sorry, I wasn't thinking either. If we choose as control and escape
>> character some little-used ASCII control characters which we are
>> sure will not appear in the input file, then there is no need to
>> escape or prepend anything, so filtering will not be necessary.
>
> Agreed. http://troff.org/54.pdf 10.1 says the first eight are OK
> except ^@, ^A, and ^D. The header and footer macros would need to
> use the new .cc though rather than `.' AIUI.
Without following much this discussion since I'm quite busy, I just
want to cite a small paragraph from groff's texinfo manual (section
`Identifiers'):
* The following input characters are invalid and are ignored if
`groff' runs on a machine based on ASCII, causing a warning
message of type `input' (see *note Debugging::, for more
details): `0x00', `0x0B', `0x0D'-`0x1F', `0x80'-`0x9F'.
Werner
