BASE <http://a.example/>

ABSTRACT <A>          /sA..........$/
                  AND
                      { <p> [0 1 2 3 4 5 6 7 8 9]+ }
         <B>          EXTENDS @<A> {}
                  AND /s.B.........$/
                  AND
                      { <p> [0 1   3 4 5 6 7 8 9]+ }

# 0 1 2 3 4 5 6 7 8 9+                         
# 0 1   3 4 5 6 7 8 9+