code: def _loadOneSource(self, sourceFName):
          
          sourceLines = open(sourceFName).readlines()
          del sourceLines[0]
          if len(sourceLines[0].split("\t"))==2:
              self._loadTwoPartSource(sourceFName, sourceLines)
          elif len(sourceLines[0].split("\t"))==3:
              self._loadThreePartSource(sourceFName, sourceLines)
          else:
              raise Error, "%s does not appear to be a source authority file"
docs: handles one authority file including format auto-detection.