[Zope] Lines data type possible in boolean OR's?

Hi, I have a small problem. When I use the lines data type in OR statements, I get an Error Type: TypeError Error Value: bad operand type(s) for | I've used them earlier on integers, like this: <dtml-if "cabinDouble | cabinTwin | cabinBunk | cabinPullman"> and it works fine. When I try the same with other data types, like this: <dtml-if "toy | additionalToys"> where "toy" is a "multiple select" type and "additionalToys" is a "lines" type. Can anyone provide me with some hints on what to do to get it working the way I want? Is typecasting necessary? Thanks in advance. Alexander. PS: please CC me if you answer :)