--EO and SF are on different ESTs (not allowed)
SELECT eosf.eo_id, 
  sneo.subnation_code eo_subn, 
  eo.element_subnational_id eo_EST, 
  est_elcode(eo.element_subnational_id) eo_elcode, 
  getsciname(eseo.sname_id) eo_sname, 
  eosf.source_feature_id, 
  snsf.subnation_code sf_subn, 
  sf.element_subnational_id sf_EST, 
  est_elcode(sf.element_subnational_id) sf_elcode,
  getsciname(essf.sname_id) sf_sname 

FROM eo, eo_source_feature eosf, 
  source_feature sf, 
  element_subnational eseo, subnation sneo,
  element_subnational essf, subnation snsf  

WHERE eo.eo_id = eosf.eo_id 
  and eosf.source_feature_id = sf.source_feature_id
  and eo.element_subnational_id = eseo.element_subnational_id 
  and sf.element_subnational_id = essf.element_subnational_id
  and eo.element_subnational_id != sf.element_subnational_id
  and eseo.subnation_id = sneo.subnation_id
  and essf.subnation_id = snsf.subnation_id