Many EHR data holders have “historical” data. Historical data is generally defined as data that was recorded in an EHR system prior to the current EHR in use at a hospital. Not all data transfers over, so it isn’t the complete record of data for a person. However, this is important data that is converted to the CDM, but it is of potentially questionable quality because it’s incomplete. We need a generic type_concept_id for this.