The following values are those used by older versions of the USGS Projection Library:
| -2 | NO_DATUM | 11 | HU_TZU_SHAN |
| -1 | UNKNOWN_DATUM | 12 | INDIAN |
| 0 | ADINDAN | 13 | NAD27 |
| 1 | ARC1950 | 14 | NAD83 |
| 2 | ARC1960 | 15 | OLD_HAWAIIAN_MEAN |
| 3 | AUSTRALIAN_GEODETIC_1966 | 16 | OMAN |
| 4 | AUSTRALIAN_GEODETIC_1984 | 17 | ORDNANCE_SURVEY_1936 |
| 5 | CAMP_AREA_ASTRO | 18 | PUERTO_RICO |
| 6 | CAPE | 19 | PULKOVO_1942 |
| 7 | EUROPEAN_DATUM_1950 | 20 | PROVISIONAL_S_AMERICAN_1956 |
| 8 | EUROPEAN_DATUM_1979 | 21 | TOKYO |
| 9 | GEODETIC_DATUM_1949 | 22 | WGS_72 |
| 10 | HONG_KONG_1963 | 23 | WGS_84 |