RPSLng and nested refine/except expressions

Larry J. Blunk wrote:

>    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.

I use that sort of construct all the time so it better continue to 
exist! See AS2764 (where I used to work) and AS7575 (my latest effort). 
RADB's reformatting makes it less obvious but it is a cascading refine.

Mark.