hi could you tell me where to write the code for iterating the list so that "exists" works properly i.e in which class [the rule executor class or a separate class] the objects have to be added to the list and iterated. how and where does "exists" go and check for the list? my dsl syntax is : [when]if {value1} is present in one box=exists List(num=={value1}) [then]set the error message as {value3}=e.setErrormessage({value3}); -- View this message in context: http://www.nabble.com/to-execute-a-DSL-with-%22exists%22-tf3338153.html#a... Sent from the drools - user mailing list archive at Nabble.com.