RE: Teletex Terminal Identifierindraft-ietf-ldapbis-syntaxes-01

["Steven Legg" <steven.legg@adacel.com.au>]

Jim,

Jim Sermersheim wrote:
> Perhaps I'm confused.
> 
> When Steven used the term "hexadecimal string", I assumed he meant:
> 
> hexstring = *hexchar
> hexchar = %x30-39 / %x41-46 / %x61-66

That's what I meant.

> 
> Which is different from:
> 
> octetstring = *OCTET
> OCTET = %x00-FF
> 
> By using a hexadecimal string, we wouldn't have to deal with escaping
> the '$' character, as it is outside the range of hexstring values.
> 
> I like the idea, but unfortunately, I believe there are existing
> implementations that encode octetstring as you have 
> prescribed, thus not
> allowing us to re-define it as hexstring.

Do these existing implementations actually pull apart the values
and do something interesting with the ttx-params ? I would expect
that LDAP only servers just store and return the bytes they're given.
So unless there are LDAP clients that try to interpret the values,
whether the ttx-params are raw octets or hexadecimal is only really
an issue for X.500 servers that need to translate between the native
encoding and the BER encoding.

Regards,
Steven

> 
> There's nothing wrong with the octetstring definition (at least in my
> mind). The original problem I was pointing out, is that when an
> octetstring is followed by a '$', we must remember (and remind) to
> escape any occurrence of the %x24 value inside the 
> octetstring (as well
> as the escape value). Otherwise, one cannot parse values of 
> the syntax.
> 
> Jim
> 
> 
> >>> Kathy Dally <kdally@mitre.org> 03/01/02 09:10AM >>>
> Hi Jim!
> 
> I'm a little confused.  A hexadecimal string is not necessarily
> octet-aligned.  So, what's the problem with the <octetstring>
> definition?
> 
> Thanks,
> Kathy
> 
> 
> Jim Sermersheim wrote:
> > 
> > Using a hexadecimal string would be nice, but there are existing
> > implementations (well, one at least) that treat an octetstring as
> Kathy
> > described (octetstring = *OCTET   , where OCTET  =  %x00-FF).
> > 
> > Actually, there are pros and cons for doing it either way.
> > 
> > Jim
> > 
> > >>> "Steven Legg" <steven.legg@adacel.com.au> 02/28/02 09:10PM >>>
> > 
> > Jim,
> > 
> > Jim Sermersheim wrote:
> > > This syntax has the encoding:
> > > teletex-id = ttx-term  0*("$" ttx-param)
> > > where ttx-param ends in an octetstring.
> > >
> > > Some escapment policy must be noted regarding the occurrence of
> %0x24
> > in
> > > the octetstring (due to the $ delimiter). It probably would have
> > been
> > > easier if ttx-param was defined as:
> > > ttx-param  = ttx-key ":" ttx-value-len ":" ttx-value
> > >
> > > but I think we're beyond going back and changing it.
> > 
> > The <octetstring> rule isn't actually defined anywhere so we're
> > free to define it to be something sensible. I suggest we make
> > it a hexadecimal string.
> > 
> > Note that the 4th edition of X.500 has deprecated this syntax.
> > The X.500 working group has even gone to the extent of removing
> > the teletexTerminalIdentifier attribute from every object class
> > that used to reference it. An option for us is to throw it out too.
> > 
> > Regards,
> > Steven
> 
>