code: def whichEncoding(self):
          
          if self.request.mode in BROWSER_REQUEST_MODES:
              if self.fields.getOpenIDNamespace() == OPENID2_NS and \
                 len(self.encodeToURL()) > OPENID1_URL_LIMIT:
                  return ENCODE_HTML_FORM
              else:
                  return ENCODE_URL
          else:
              return ENCODE_KVFORM
docs: How should I be encoded?
  
          @returns: one of ENCODE_URL, ENCODE_HTML_FORM, or ENCODE_KVFORM.
  
          @change: 2.1.0 added the ENCODE_HTML_FORM response.