[rules-users] "extends" in rules

Hi, I found an example on using "extends" to extend a rule from another rule. Using extends would only include the WHEN side of the rule. I want to use the variable defined in the parent rule in sub rule ,something like below example,how do i do that? rule A when $a:String( ) eval($a=="abc") then do something end rule B extends A when $b:String( ) $c:SomeClass() then $c.someMethod($a,$b) //i am not able to use $a here end Any suggestions? Thanks Chandana