spf-discuss
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RE: Re: purely dual-format approach

2004-10-30 13:40:13

On Sat, 30 Oct 2004, guy wrote:

What about this?
When using sc, and scope uses "+" or "-" then the current set of scope(s)
will be modified.  If "+" or "-" is not used then a new set of scopes is
defined.  If a "-" is used then any other scope without "+" or "-" will
assume "+" (or we could say: if any 1 scope used "+" or "-" all other scopes
must also use "+" or "-", if not, syntax error).  The first set of scoped
defined can not use "+" or "-" since the set is not yet defined (or we could
just assume the default is an empty set).

Examples:
"sc=s1 m1 sc=s2 m2 m3 m4"
m1 is in s1 scope
m2, m3, m4 is in s2 scope

"sc=s1 m1 sc=-s1,s2 m2 m3 m4"  ##s2 is assumed to be +s2
m1 is in s1 scope
m2, m3, m4 is in s2 scope

"sc=s1 m1 sc=+s2 m2 m3 m4"
m1 is in s1 scope
m2, m3, m4 is in s1 and s2 scopes

"sc=s1,s2 m1 sc=-s2 m2 m3 m4"
m1 is in s1 and s2 scopes
m2, m3, m4 is in s1 scope
 
This looks good to me. I believe it gives more expressive scoping syntax
and is syntaticallly possible to define. The only thing is that I don't
like if we we have to foce somebody to have different meaning depending on 
if there was - or not. So I propose it that if there was no +/- that it 
means that all old scopes are closed and new one is open. But if there is 
+/- than it has meaning of modifiying existing set. So the only modified 
example from above is:

"sc=s1 m1 sc=-s1,+s2 m2 m3 m4"
 m1 is in s1 scope
 m2, m3, m4 is in s2 scope

And this really is like a scoping parameter allowing for opting in and 
opting out of various meanings. Also if somebody wants to have v=spf1
stand for all scopes (i.e. like what Meng and Microsoft want), then the 
following will specifically say "no pra":

 v=spf? sc=-p .... -all

---
William Leibzon
Elan Networks
william(_at_)elan(_dot_)net