[Zope] External Method Working Directory?

Folks, I have an external method that at this point is made up of nothing but os.getcwd() and lives in my Extensions directory. When it is run, it reports the working directory as being one of my Products directories. Can anyone tell me what the default working directory for an external method is? Further, I need this to create a file temporarily in Extensions. I would prefer not to have to hardwire the location of Extension into the code, since that would make the script non-portable to other instances easily. Any advice on this would be appreciated. J. P. Withers