[Zope] Generating and Downloading PDF.

Hi guys, I'm creating a pdf using reportlab, after the canvas.close() I put the following code inside a External Method: R = self.REQUEST.RESPONSE R.setHeader('content-type', 'application/rtf') R.setHeader('content-length', str(len(data))) R.write(data) But I receive the following error: *Error Type: NameError* *Error Value: global name 'self' is not defined Is there some import wich I have been missing? Fernando Lujan