[Zope] property of type 'lines' for objects on file system

I'd like to put a property of type 'lines' to an object on the file system throught its corresponding .metadata file, but don't know the syntax I shall use in the file. I remember having seen recently a similar question, and the answer seems to be that a patch is required for FSDV to recognize a lines-typed property. But I can't find the thread anymore. Can anyone give me a pointer? Thansk for helping. Hong Yuan