anchor.diff:  STEM_TABLE,ROUTE_SOURCE_VALUE,DRUG_EXPOSURE,ROUTE_SOURCE_VALUE
   STEM_TABLE,DOSE_UNIT_SOURCE_VALUE,DRUG_EXPOSURE,DOSE_UNIT_SOURCE_VALUE
   STEM_TABLE,PERSON_ID,DEVICE_EXPOSURE,PERSON_ID
  +STEM_TABLE,ID,DEVICE_EXPOSURE,DEVICE_EXPOSURE_ID
   STEM_TABLE,CONCEPT_ID,DEVICE_EXPOSURE,DEVICE_CONCEPT_ID
   STEM_TABLE,START_DATE,DEVICE_EXPOSURE,DEVICE_EXPOSURE_START_DATE
   STEM_TABLE,END_DATE,DEVICE_EXPOSURE,DEVICE_EXPOSURE_END_DATE
  
positive.code: STEM_TABLE,UNIT_SOURCE_VALUE,OBSERVATION,UNIT_SOURCE_VALUE
  STEM_TABLE,QUALIFIER_SOURCE_VALUE,OBSERVATION,QUALIFIER_SOURCE_VALUE
  STEM_TABLE,PERSON_ID,PROCEDURE_OCCURRENCE,PERSON_ID
  STEM_TABLE,CONCEPT_ID,PROCEDURE_OCCURRENCE,PROCEDURE_CONCEPT_ID
  STEM_TABLE,START_DATE,PROCEDURE_OCCURRENCE,PROCEDURE_DATE
  STEM_TABLE,TYPE_CONCEPT_ID,PROCEDURE_OCCURRENCE,PROCEDURE_TYPE_CONCEPT_ID
  
negative.code: STEM_TABLE,SOURCE_VALUE,PROCEDURE_OCCURRENCE,PROCEDURE_SOURCE_VALUE
  STEM_TABLE,SOURCE_CONCEPT_ID,PROCEDURE_OCCURRENCE,PROCEDURE_SOURCE_CONCEPT_ID
  STEM_TABLE,QUALIFIER_SOURCE_VALUE,PROCEDURE_OCCURRENCE,QUALIFIER_SOURCE_VALUE
  STEM_TABLE,PERSON_ID,SPECIMEN,PERSON_ID
  STEM_TABLE,ID,SPECIMEN,SPECIMEN_ID
  STEM_TABLE,CONCEPT_ID,SPECIMEN,SPECIMEN_CONCEPT_ID
  STEM_TABLE,TYPE_CONCEPT_ID,SPECIMEN,SPECIMEN_TYPE_CONCEPT_ID
  STEM_TABLE,START_DATE,SPECIMEN,SPECIMEN_DATE
  