> nroff(1) says
>
> If neither the GROFF_TYPESETTER environment variable nor the -T
> command line option (which overrides the environment variable)
> specifies a (valid) device, nroff checks the current locale to
> select a default output device.
>
> Why is it useful to have nroff ignore a duff -T value and fall back as
> if it was unspecified?
I can't remember...
> $ echo '\[-+]' | nroff -Tlatin1 | grep .
> -+
> $
>
> latin1(7) here says
>
> Oct Dec Hex Char Description
> ───────────────────────────────────────────
> ...
> 261 177 B1 ± PLUS-MINUS SIGN
>
> and that seems defined in the device's fonts
>
> $ fgrep +- font/devlatin1/R
> +- 24 0 0261
> t+- "
> $
>
> so why isn't grotty outputing the single byte for it?
It does. However, in your nroff line above, you are searching for
\[-+], not \[+-], which is not the same.
> $ echo '\[-+]' | groff >/dev/null
> <standard input>:1: warning: can't find special character `-+'
> $
>
> The PostScript glyph name is `plusminus'.
Again, this is \[+-], not \[-+].
Werner
