$output->add_definitions ( { a => '$result = "HELLO"', b => '$result = "$data WORLD"', c => '$result = "$data!!"' } ) #$data is the string inside the tag so if you have a #tag which contains the string "HELLO", then $data #will be equal to "HELLO" when the tag is being computed print $output->compute(" "); #the interpreter ignores tags that it does not have #definitions for