anchor.diff:  NOTE,note_date,Yes,date,The date the note was recorded.,,No,No,,,,,
   NOTE,note_datetime,No,datetime,,If time is not given set the time to midnight.,No,No,,,,,
   NOTE,note_type_concept_id,Yes,integer,The provenance of the note. Most likely this will be EHR. ,"Put the source system of the note, as in EHR record. [Accepted Concepts](https://athena.ohdsi.org/search-terms/terms?standardConcept=Standard&domain=Type+Concept&page=1&pageSize=15&query=).",No,Yes,CONCEPT,CONCEPT_ID,Type Concept,,
  -NOTE,note_class_concept_id,Yes,integer,"A Standard Concept Id representing the HL7 LOINC
  +NOTE,note_class_concept_id,Yes,integer,"A Standard Concept Id representing the HL7 LOINC
   Document Type Vocabulary classification of the note.",Map the note classification to a Standard Concept. For more information see the ETL Conventions in the description of the NOTE table. [Accepted Concepts](https://athena.ohdsi.org/search-terms/terms?standardConcept=Standard&conceptClass=Doc+Kind&conceptClass=Doc+Role&conceptClass=Doc+Setting&conceptClass=Doc+Subject+Matter&conceptClass=Doc+Type+of+Service&domain=Meas+Value&page=1&pageSize=15&query=). This Concept can alternatively be represented by concepts with the relationship 'Kind of (LOINC)' to [706391](https://athena.ohdsi.org/search-terms/terms/706391) (Note).,No,Yes,CONCEPT,CONCEPT_ID,,,
   NOTE,note_title,No,varchar(250),The title of the note.,,No,No,,,,,
   NOTE,note_text,Yes,varchar(MAX),The content of the note.,,No,No,,,,,
  
positive.code: DRUG_ERA,person_id,Yes,integer,,,No,Yes,PERSON,PERSON_ID,,,
  DRUG_ERA,drug_concept_id,Yes,integer,The Concept Id representing the specific drug ingredient.,,No,Yes,CONCEPT,CONCEPT_ID,Drug,Ingredient,
  DRUG_ERA,drug_era_start_date,Yes,datetime,,"The Drug Era Start Date is the start date of the first Drug Exposure for a given ingredient, with at least 31 days since the previous exposure. ",No,No,,,,,
  DRUG_ERA,drug_era_end_date,Yes,datetime,,"The Drug Era End Date is the end date of the last Drug Exposure. The End Date of each Drug Exposure is either taken from the field drug_exposure_end_date or, as it is typically not available, inferred using the following rules:
  For pharmacy prescription data, the date when the drug was dispensed plus the number of days of supply are used to extrapolate the End Date for the Drug Exposure. Depending on the country-specific healthcare system, this supply information is either explicitly provided in the day_supply field or inferred from package size or similar information.
  For Procedure Drugs, usually the drug is administered on a single date (i.e., the administration date).
  A standard Persistence Window of 30 days (gap, slack) is permitted between two subsequent such extrapolated DRUG_EXPOSURE records to be considered to be merged into a single Drug Era.",No,No,,,,,
  DRUG_ERA,drug_exposure_count,No,integer,,,No,No,,,,,
  DRUG_ERA,gap_days,No,integer,,"The Gap Days determine how many total drug-free days are observed between all Drug Exposure events that contribute to a DRUG_ERA record. It is assumed that the drugs are ""not stockpiled"" by the patient, i.e. that if a new drug prescription or refill is observed (a new DRUG_EXPOSURE record is written), the remaining supply from the previous events is abandoned.   The difference between Persistence Window and Gap Days is that the former is the maximum drug-free time allowed between two subsequent DRUG_EXPOSURE records, while the latter is the sum of actual drug-free days for the given Drug Era under the above assumption of non-stockpiling.",No,No,,,,,
  
negative.code: VISIT_OCCURRENCE,visit_concept_id,Yes,integer,"This field contains a concept id representing the kind of visit, like inpatient or outpatient. All concepts in this field should be standard and belong to the Visit domain.","Populate this field based on the kind of visit that took place for the person. For example this could be ""Inpatient Visit"", ""Outpatient Visit"", ""Ambulatory Visit"", etc. This table will contain standard concepts in the Visit domain. These concepts are arranged in a hierarchical structure to facilitate cohort definitions by rolling up to generally familiar Visits adopted in most healthcare systems worldwide. [Accepted Concepts](https://athena.ohdsi.org/search-terms/terms?domain=Visit&standardConcept=Standard&page=1&pageSize=15&query=).",No,Yes,CONCEPT,CONCEPT_ID,Visit,,
  VISIT_OCCURRENCE,visit_start_date,Yes,date,"For inpatient visits, the start date is typically the admission date. For outpatient visits the start date and end date will be the same.","When populating VISIT_START_DATE, you should think about the patient experience to make decisions on how to define visits. In the case of an inpatient visit this should be the date the patient was admitted to the hospital or institution. In all other cases this should be the date of the patient-provider interaction.",No,No,,,,,
  VISIT_OCCURRENCE,visit_start_datetime,No,datetime,,"If no time is given for the start date of a visit, set it to midnight (00:00:0000).",No,No,,,,,
  VISIT_OCCURRENCE,visit_end_date,Yes,date,For inpatient visits the end date is typically the discharge date.,"Visit end dates are mandatory. If end dates are not provided in the source there are three ways in which to derive them:
  - Outpatient Visit: visit_end_datetime = visit_start_datetime
  - Emergency Room Visit: visit_end_datetime = visit_start_datetime
  - Inpatient Visit: Usually there is information about discharge. If not, you should be able to derive the end date from the sudden decline of activity or from the absence of inpatient procedures/drugs.
  - Non-hospital institution Visits: Particularly for claims data, if end dates are not provided assume the visit is for the duration of month that it occurs.
  For Inpatient Visits ongoing at the date of ETL, put date of processing the data into visit_end_datetime and visit_type_concept_id with 32220 ""Still patient"" to identify the visit as incomplete.
  - All other Visits: visit_end_datetime = visit_start_datetime. If this is a one-day visit the end date should match the start date.",No,No,,,,,
  VISIT_OCCURRENCE,visit_end_datetime,No,datetime,,"If no time is given for the end date of a visit, set it to midnight (00:00:0000).",No,No,,,,,
  VISIT_OCCURRENCE,visit_type_concept_id,Yes,Integer,"Use this field to understand the provenance of the visit record, or where the record comes from.","Populate this field based on the provenance of the visit record, as in whether it came from an EHR record or billing claim. [Accepted Concepts](https://athena.ohdsi.org/search-terms/terms?domain=Type+Concept&standardConcept=Standard&page=1&pageSize=15&query=).",No,Yes,CONCEPT,CONCEPT_ID,Type Concept,,
  