bug#10019: sort options -Mn are incompatible

[Jim Meyering]

Eric Blake wrote:
> Sure.  Here's the current state of things in patch format; any last
> objections before I push this?
...
> Subject: [PATCH] sort: clarify wording on -k syntax
>
> * src/sort.c (usage): Use KEYDEF instead of POS, and call out the
> specific OPTS that can occur in KEYDEF.
> Based on a report by Lars Noodén, http://bugs.gnu.org/10019
...
> +KEYDEF is F[.C][OPTS][,F[.C][OPTS]] for start and stop position, where
> F is a\n\
> +field number and C a character position in the field; both are origin
> 1, and\n\
> +the stop position defaults to the line's end.  If neither -t nor -b is
> in\n\
> +effect, characters in a field are counted from the beginning of the
> preceding\n\
> +whitespace.  OPTS is one or more single-letter ordering options
> [bdfgiMhnRrV],\n\
> +which override global ordering options for that key.  If no key is
> given, use\n\
> +the entire line as the key.\n\

Thanks.  That reads well.
Note that some tool of yours appears to have split many lines of that patch.