function getLetter100kID(column, row, parm) {
    // colOrigin and rowOrigin are the letters at the origin of the set
    var index = parm - 1;
    var colOrigin = SET_ORIGIN_COLUMN_LETTERS.charCodeAt(index);
    var rowOrigin = SET_ORIGIN_ROW_LETTERS.charCodeAt(index);

    // colInt and rowInt are the letters to build to return
    var colInt = colOrigin + column - 1;
    var rowInt = rowOrigin + row;
    var rollover = false;

    if (colInt > Z) {
      colInt = colInt - Z + A - 1;
      rollover = true;
    }

    if (colInt === I || (colOrigin < I && colInt > I) || ((colInt > I || colOrigin < I) && rollover)) {
      colInt++;
    }

    if (colInt === O || (colOrigin < O && colInt > O) || ((colInt > O || colOrigin < O) && rollover)) {
      colInt++;

      if (colInt === I) {
        colInt++;
      }
    }

    if (colInt > Z) {
      colInt = colInt - Z + A - 1;
    }

    if (rowInt > V) {
      rowInt = rowInt - V + A - 1;
      rollover = true;
    }
    else {
      rollover = false;
    }

    if (((rowInt === I) || ((rowOrigin < I) && (rowInt > I))) || (((rowInt > I) || (rowOrigin < I)) && rollover)) {
      rowInt++;
    }

    if (((rowInt === O) || ((rowOrigin < O) && (rowInt > O))) || (((rowInt > O) || (rowOrigin < O)) && rollover)) {
      rowInt++;

      if (rowInt === I) {
        rowInt++;
      }
    }

    if (rowInt > V) {
      rowInt = rowInt - V + A - 1;
    }

    var twoLetter = String.fromCharCode(colInt) + String.fromCharCode(rowInt);
    return twoLetter;
  }
Get the two-letter MGRS 100k designator given information
translated from the UTM northing, easting and zone number.

@private
@param {number} column the column index as it relates to the MGRS
       100k set spreadsheet, created from the UTM easting.
       Values are 1-8.
@param {number} row the row index as it relates to the MGRS 100k set
       spreadsheet, created from the UTM northing value. Values
       are from 0-19.
@param {number} parm the set block, as it relates to the MGRS 100k set
       spreadsheet, created from the UTM zone. Values are from
       1-60.
@return two letter MGRS 100k code.