LOINC description : The patient identifier is a unique alphanumeric string that identifies a specific
patient and is assigned by a specific organization (the assigning authority) that
should be reported using [LOINC: 76698-0]. In HL7 v2 messages, the patient identifier
is reported in PID-3.1 and the assigning authority in PID-3.4. Examples of patient
identifiers are medical record number, driver's license number and Social Security
number, and their corresponding assigning authorities are the appropriate healthcare
facility, state motor vehicle administration and the Social Security Administration,
respectively.;