def export(self, version, export_dir):
        """
        Create prov entities and activities.
        """
        atts = (
            (PROV['label'], self.label),
            (PROV['type'], NIDM_SEARCH_SPACE_MASK_MAP),
            (NIDM_RANDOM_FIELD_STATIONARITY, self.rf_stationarity),
            (NIDM_IN_COORDINATE_SPACE, self.coord_space.id),
            (NIDM_SEARCH_VOLUME_IN_VOXELS, self.search_volume_in_voxels),
            (NIDM_SEARCH_VOLUME_IN_UNITS, self.search_volume_in_units),
            (NIDM_SEARCH_VOLUME_IN_RESELS, self.search_volume_in_resels),
            (NIDM_RESEL_SIZE_IN_VOXELS, self.resel_size_in_voxels))

        # Noise FWHM was introduced in NIDM-Results 1.1.0
        if self.noise_fwhm_in_voxels is not None:
            if (version['major'] > 1) or \
               (version['major'] >= 1 and
                    (version['minor'] > 0 or version['revision'] > 0)):
                atts = atts + (
                    (NIDM_NOISE_FWHM_IN_VOXELS, self.noise_fwhm_in_voxels),
                    (NIDM_NOISE_FWHM_IN_UNITS, self.noise_fwhm_in_units))

        if self.expected_num_voxels is not None:
            atts = atts + ((NIDM_EXPECTED_NUMBER_OF_VOXELS_PER_CLUSTER,
                            self.expected_num_voxels),)

        if self.expected_num_clusters is not None:
            atts = atts + ((NIDM_EXPECTED_NUMBER_OF_CLUSTERS,
                            self.expected_num_clusters),)

        if self.height_critical_fwe05 is not None:
            atts = atts + ((NIDM_HEIGHT_CRITICAL_THRESHOLD_FWE_05,
                            self.height_critical_fwe05),)

        if self.height_critical_fdr05 is not None:
            atts = atts + ((NIDM_HEIGHT_CRITICAL_THRESHOLD_FDR_05,
                            self.height_critical_fdr05),)

        if self.extent_critical_fwe05 is not None:
            atts = atts + ((
                SPM_SMALLEST_SIGNIFICANT_CLUSTER_SIZE_IN_VOXELS_FWE05,
                self.extent_critical_fwe05),)

        if self.extent_critical_fdr05 is not None:
            atts = atts + ((
                SPM_SMALLEST_SIGNIFICANT_CLUSTER_SIZE_IN_VOXELS_FDR05,
                self.extent_critical_fdr05),)

        if self.search_vol_geom is not None:
            atts = atts + ((SPM_SEARCH_VOLUME_RESELS_GEOMETRY,
                            self.search_vol_geom),)

        if self.noise_roughness:
            atts = atts + ((NIDM_NOISE_ROUGHNESS_IN_VOXELS,
                            self.noise_roughness),)

        # Create "Search Space Mask map" entity
        self.add_attributes(atts)
Create prov entities and activities.