a sort key specifies a range of fields. From Karl O. Pinc.
That is, given the input line @w{@samp{ foo bar}}, @code{sort} breaks it
into fields @w{@samp{ foo}} and @w{@samp{ bar}}. The field separator is
not considered to be part of either the field preceding or the field
-following.
+following. But note that sort fields that extend to the end of the line,
+as @samp{-k 2}, or sort fields consisting of a range, as @samp{-k 2,3},
+retain the field separators present between the endpoints of the range.
@item -T @var{tempdir}
@opindex -T