The designation of a control point is a name chosen by the surveyor to identify the station. The NGS blue book guidelines suggest that designations of vertical control stations be named in order of their establishment within each state, beginning with "A", "B", etc., then with "A1", "B1", etc.
The guidelines suggest that horizontal control stations be named to suggest a local geographic location or feature. The name should be unique within a county, and preferably unique within the state.
The designation is similar to the stamping on the disk, but not identical. Dates, agency names, and other information that may be in the stamping are not included in the designation.