Subj : Max subject length: 71 or 72 chars?
To   : Ward Dossche
From : Rob Swindell
Date : Sun Aug 25 2019 02:53 pm

  Re: Max subject length: 71 or 72 chars?
  By: Ward Dossche to Alexey Vissarionov on Sun Aug 25 2019 04:10 pm

 > Alexey,
 >
 >  WD>> Please be aware that this "discussion" is nothing more than a single
 >  WD>> message by a single person...
 >
 >  AV> ... with nobody been able to disprove that :-)
 >
 > Nothing needed to be disproven as the spec is pretty straightforward.

I disagree. I think it's ambiguous and incomplete, if not misleading.

 > It's just that native english speakers needed to be made aware.

Is FTS-1 available in another language, where it's possibly more complete? I'm not clear what "english speaking" has to do with it.

Here's what FTS-1 has to say about the message subject in Stored Messages in
section B1:
              +-----------------------+-----------------------+
       72  48 |                                               |
              ~                    subject                    ~
              |                   72  bytes                   |
              +-----------------------+-----------------------+
....
                  subject(72)       (* see FileList below *)

No mention that a null-terminator is required.
No mention that the actual/usable number of characters in a message subject is in fact 71 characters (not 72).

Now, section C1 (Packed Message definition) is little better:

              +-----------------------+-----------------------+
              |                    subject                    |
              ~                  max 72 bytes                 ~
              |                null terminated                |
              +-----------------------+-----------------------+
....
                    subject{72}       (* Null terminated *)

But again, it should be made clear that the "72 bytes" here includes the required null terminator, so a message subject is in fact limited to a maxmimum length of 71 characters.

.