Re: RE: I-D ACTION:draft-ietf-asid-mime-direct-02.txt

[John C Klensin <klensin@xxxxxxxxxxxxxxxxxxxx>]

On Thu, 22 Aug 1996 18:25:53 -0700  "Alec Dun (Exchange)" 
<AlecDu@Exchange.Microsoft.com> wrote:
>...
> 2.  Efficiency in repeated properties.  To increase efficiency, I
> propose that we allow properties which have the same name to be repeated
> without the name.  In this scheme, the repeated property would inherit
> the attributes from the previous property.  For example:
> 
> CN:  Frank Arthur
> CN:  Arthur Frank
> CN:  Frank
> 
> would become
> 
> CN:  Frank Arthur
> :Arthur Frank
> :Frank

Alec,

>From a language design standpoint, I'd recommend against this, 
at least in this form.  It has some slightly uncomfortable 
parsing properties relative for environments in which one might 
want to implement things by, e.g., quickly sweeping through the 
file using a hash on the names to insert properties in a list.  
More generally, one doesn't want to need to look ahead and then 
back up if that is avoidable.  Doing things with omitted 
property tags implies that one needs strong ordering rules and, 
typically, an extra algorithmic step to guard against bad 
behavior from violations of those rules.  One can avoid those 
problems by a careful choice of parsing procedures, but we try 
to avoid imposing that type of constraint unless it is clearly 
needed.

As an alternative, if you want to omit repeated property names, 
consider introducing an iterated list, e.g.,
   CN: { Frank Arthur, Arthur Frank,
                Frank }
in C-ish style or
    <CN> Frank Arthur, Arthur Frank, Frank </CN>
if HTML-ish style.

I'll not comment on the other two suggestions at this time.

    john