Client Registry Exchange: last_known_location format

This issue tracks the discussion of whether to modify the PFIF last_know_location element currently included in the TEC Client Registry Exchange specification, v. 1.0:

last_known_location (Unicode string, optional):

A free-form description of the last known location of the person, which can be expressed as geographical coordinates. To specify geographic coordinates in this field, give the latitude in decimal degrees (positive for north), then a comma, then the longitude in decimal degrees (positive for east) . If this field is present, the text field of this note (the next field listed below) should describe HOW the person's location was determined.