bug#35343: sort: printing characters: define

[L A Walsh]

On 4/20/2019 6:54 AM, 積丹尼 Dan Jacobson wrote:
> (info "(coreutils) sort invocation") says
>
> ‘-i’
> ‘--ignore-nonprinting’
>      Ignore nonprinting characters.  The ‘LC_CTYPE’ locale determines
>      character types...
>   
----
    @ location:
 
https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/basedefs/V1_chap07.html#tag_07_03_01

LC CTYPE is defined by POSIX for the 'POSIX' or 'C' locale.  It is
relative (defined) as specified by the current locale.
> Well this leaves the user high and dry trying to figure out what you
> mean by printing characters.
>   
If the user is wet and water is introduced into the printing medium,
ink smearing or other malfunctions may occur that might hinder
performance, recognition and validation w/r/t any specification.
(str8 face)
> Is SPC a printing character he wonders. It makes the printer head
> advance one unit, whereas ESC doesn't.
>   
SPACE is a printing character, ESC is a control-character.  All
control characters are *excluded* from the the class 'PRINT'.

> So at least mention the ASCII range [A-Z...] of what your are talking
> about. It would only take up a word or two of the INFO page.
>
> Anyway, each program might have their own idea of "printing characters"
> as well as grandpa down the hall's definition. So the user is left unsure.
>   
In that regard, if each program has its own definition, then different
programs would find it hard to talk with each other.  In order for
programs to inter-operate with each other, it would be best if all
programs being used would use the same specification for details like
"printing character".  Having each program document shared and basic
definitions would tend to be redundant.  Instead the reader should be
aware of standards (such as character definitions and classifications)
for their platform. 

Accordingly, it would be redundant to include extra information about
needed standards with each program.  No?  :-)