+#################### cross-relations tables
+# authority x user (pis) association
+authority_pi_table = \
+ Table ( 'authority_pi', Base.metadata,
+ Column ('authority_id', Integer, ForeignKey ('records.record_id'), primary_key=True),
+ Column ('pi_id', Integer, ForeignKey ('records.record_id'), primary_key=True),
+ )
+# slice x user (researchers) association
+slice_researcher_table = \
+ Table ( 'slice_researcher', Base.metadata,
+ Column ('slice_id', Integer, ForeignKey ('records.record_id'), primary_key=True),
+ Column ('researcher_id', Integer, ForeignKey ('records.record_id'), primary_key=True),
+ )
+