A convenient ASCII format saves data in a self-explaining matrix. The old style has a verbal header:
YYYY MM DD HH MM SS HAN X HAN Y HAN Z NUR X NUR Y NUR Z ---------------------------------------------------------------------- 1999 02 03 04 00 00 13759.4 1715.1 49852.7 14918.9 1504.5 49443.8 1999 02 03 04 00 10 13759.4 1715.2 49852.5 14919.0 1504.5 49443.9 1999 02 03 04 00 20 13759.4 1715.2 49852.7 14919.0 1504.5 49443.8 1999 02 03 04 00 30 13759.1 1715.2 49853.0 14918.9 1504.5 49443.8 1999 02 03 04 00 40 13759.4 1715.4 49852.9 14918.8 1504.5 49443.7 1999 02 03 04 00 50 13758.9 1715.1 49852.9 14918.7 1504.4 49443.8 1999 02 03 04 01 00 13759.5 1714.8 49852.9 14918.7 1504.3 49443.8 and so on.
The new style has a numeric header giving the geographic latitude and longitude of each site (in degrees). This file can be directly loaded e.g. into MatLab:
0 0 0 0 0 0 62.30 26.65 0 60.50 24.65 0 1999 02 03 04 00 10 13759.4 1715.1 49852.7 14918.9 1504.5 49443.8 and so on.
X,Y and Z are the geographic north, east and downward components. The unit is nT. Missing value = 99999.9.