RPSLng and nested refine/except expressions

Historical perspective:
	- first there was the nested syntax
	- then it got replaced by the cascading syntax since the sematics were
simpler
	- one example using the nested syntax unfortunately stayed in the
document.

Note that RPSL only defines semantics for the cascading form.

On Fri, 2004-05-07 at 14:17, Larry J. Blunk wrote:
>   In the -04 version of the RPSLng draft, the structured policy syntax was
> updated to allow nested refines and excepts in policy expressions.  I.e.
> 
>   refine {
>     <expression>
>      refine {
>          <expression>
>      }
>   }
> 
>    Examples of such expressions are given both RFC2622 and the RPSLng
> draft.   However, the original RFC2622 syntax did not actually allow such
> expressions.
> 
>    However, in the process of implementing and running the syntax check
> on existing objects, I have found examples of the following:
> 
>   refine {
>      <expression>
>      } refine {
>         <expression>
>      }
> 
>      See, for example, AS7574 in the RADB.  Unfortunately, such expressions
> are invalid in the lastest RPSLng draft.   Are such expressions semantically
> identical to nested refines/excepts?    Should both this form and the nested
> form be allowed.    I have come up with a minor modification to the -04
> syntax that would allow both, but I'm not sure if it is a good idea or not.
> 
>    -Larry
> 
> 
> 
>   
-- 
Cengiz Alaettinoglu <Cengiz_Alaettinoglu at yahoo.com>