Re: Proposal for ISSUE-32, curly braces in joinCondition

> However, we still have to handle the case where the join is across multiple
> columns. I propose to do it by using RDF lists, like this:
>
>   [] rr:parentTriplesMap <#TriplesMap1>;
>      rr:joinChild ("col1","col2");
>      rr:joinParent ("col1","col2");
>
>
How about:

  [] rr:parentTriplesMap <#TriplesMap1>;
     rr:joinCondition [ rr:child "col1";
                              rr:parent "col1" ];
     rr:joinCondition [ rr:child "col2";
                              rr:parent "col2" ];

Slightly more verbose, but it keeps the two columns that are being checked
closer to each other (i.e. the child column is more explicitly paired up
with its parent column). Also, it seems like lists end up causing pain in
RDF.

-David