Teradata Database follows the MGRS convention of truncating, rather than rounding values during the conversion. The net effect of the truncation is to shift points to the south and west (the lowest point in each rectangle).
MGRS coordinates employ one of two lettering schemes to denote row identifiers in the grid system: MGRS-Old or MGRS-New. During conversions to and from MGRS, the MGRS lettering scheme in the returned coordinates (for the TO_MGRS function) or expected as input (to the FROM_MGRS function) depends on the spatial reference system from or to which the coordinates are being converted. If the spatial reference system is based on the Bessel, Clarke 1866, or Clarke 1880 reference ellipsoid, the MGRS coordinates use the MGRS-Old lettering scheme. Conversion to or from all other spatial reference systems use the MGRS-New scheme.