r'[a-zA-Z]+

def t_ID(self, t):
        r'[a-zA-Z]+'
        if t.value in self._RESERVED.keys():
            t.type = self._RESERVED[t.value]
            return t

        if Information.is_valid_symbol(t.value) or \
                Information.is_valid_category(t.value):
            t.type = self._INFORMATION_UNIT
            return t

        if Duration.is_valid_symbol(t.value):
            t.type = self._DURATION_UNIT
            return t

        raise LexingError('Unrecognised token or unit \'{0.value}\' at '
                          'position {0.lexpos}'.format(t))