To determine the GCDB-ID for a 1/16 section corner on the boundaries of the section, take the appropriate section corner ID and place a 20 or a 60 in the last two digits of the prefix or suffix depending on the distance along the line and the direction from that section corner.
To determine the GCDB-ID for the center 1/16 section corners take the appropriate 1/4 section corner and place a 20 or 60 in the last two places of the prefix on the E and W centerline and of the suffix on the N and S centerlines depending on the distance along the line from the 1/4 section corner.
The NE, SE, SW and NW 1/16 section corners have the prefix of the corner to the north or south and the suffix of the corner to the east and west.