def METHOD_NAME( self, config ):
    """
    Queries Tier0DataSvc to get the most recent Global Tag for a given workflow.
    Parameters:
    config: Tier0DataSvc API call for the workflow to be looked for;
    @returns: a string with the Global Tag name.
    Raises if connection error, bad response, timeout after retries occur, or if no Global Tags are available.
    """
    data = self._queryTier0DataSvc( os.path.join( self._uri, config ) )
    gtnames = sorted(unique( [ str( di[ 'global_tag' ] ) for di in data['result'] if di[ 'global_tag' ] is not None ] ))
    try:
        recentGT = gtnames[-1]
        return recentGT
    except IndexError:
        errStr = """No Global Tags for \"%s\" are available in Tier0DataSvc from URL \"%s\"""" %( config, os.path.join( self._uri, config ) )
        if self._proxy:
            errStr += """ using proxy \"%s\".""" %( str( self._proxy ), )
    raise Tier0Error( errStr )