def buildType(columns=[], extra=[]):
        """Build a table

        :param list columns: List of column names and types. eg [('colA', 'd')]
        :param list extra: A list of tuples describing additional non-standard fields
        :returns: A :py:class:`Type`
        """
        return Type(id="epics:nt/NTTable:1.0",
                    spec=[
                    ('labels', 'as'),
                    ('value', ('S', None, columns)),
                    ('descriptor', 's'),
                    ('alarm', alarm),
                    ('timeStamp', timeStamp),
                    ] + extra)
Build a table

        :param list columns: List of column names and types. eg [('colA', 'd')]
        :param list extra: A list of tuples describing additional non-standard fields
        :returns: A :py:class:`Type`