def export(self, version, export_dir):
        """
        Create prov entities and activities.
        """
        atts = [
            (PROV['type'], self.type),
        ]

        atts += [
            (PROV['label'], self.label)
        ]

        if self.extent_rsl is not None:
            atts += [
                (NIDM_CLUSTER_SIZE_IN_RESELS, self.extent_rsl),
            ]

        if self.extent is not None:
            atts += [
                (NIDM_CLUSTER_SIZE_IN_VOXELS, self.extent),
            ]

        if version['num'] == "1.0.0":
            atts += [
                (NIDM_USER_SPECIFIED_THRESHOLD_TYPE, self.user_threshold_type),
                (NIDM_P_VALUE_UNCORRECTED, self.p_uncorr),
                (NIDM_P_VALUE_FWER, self.p_corr)
            ]
        else:
            atts += [
                (PROV['type'], self.threshold_type)
            ]
            if self.value is not None:
                atts += [
                    (PROV['value'], self.value)
                ]

        if self.equiv_thresh is not None:
            for equiv in self.equiv_thresh:
                atts += [
                    (NIDM_EQUIVALENT_THRESHOLD, equiv.id)
                ]

        self.add_attributes([(k, v) for k, v in atts if v is not None])