The PID is a 6-character code that the NGS uses to keep track of ["control"] points in their ["NSRS"] computer database. This code was invented when the ["NGS"] computerized its records. Prior that computerization effort, each control point had a "designation", or name that adequately identified it within its local area, but which may have been duplicated in other parts of the country. The "designation" is a name chosen by the surveyor who establishes the point. The "PID" is chosen by the NGS.