OID value: 1.2.840.113518.104.22.168
The unstructuredAddress attribute type specifies the address or addresses of a subject as an unstructured directory string. The interpretation of unstructured addresses is intended to be specified by certificate issuers etc; no particular interpretation is required.
URL for further info: http://www.rsalabs.com/pkcs/pkcs-9/index.html
See also the OID Repository website reference for 1.2.840.113522.214.171.124