rule RuleA {
from s : IN!A (s.oclIsOfType(IN!A))
to t : OUT!A (
        attributeA <- newAA
       )
    newAA : OUT!AA
}
rule RuleB extends RuleA{
from s: IN!B 
to t : OUT!B (
        attributeA <- newBB
       )
    newBB : OUT!BB
}