IAGA file format for one minute or denser values: - Record Length 4 characters (1440) - Length of one record 3 in minutes - Type of data 2 00 = observatory; 01 = temporary st.; - Station Identification 6 (e.g. 3 numbers, 3 letters) - Geographic latitude 5 in 0.01 degrees (space or sign and 4 digits) - Geographic longitude 5 in 0.01 degrees East - Free 23 - Year 4 - Month 2 - Day 2 - Hour 2 00...23 UT - Minute 2 00...59. The first minute of record. - Interval between datapoints 2 in seconds - How produced 1 0 = digital recording,; 1 = digitized from primary recordings; 2 = digitized from supplementary recordings; 9 = unknown. - Filter breakpoint 4 0000 if values are means between data points. Otherwise period in seconds at which low pass filter is 3 db down (0.7 amplitude). 9999 if no filtering was employed. - Filter slope 2 db per octave, i.e. 6,12,18 db/octave or measured equivalent for numerical filter. - Baseline information 1 1 = final data, absolute baseline, accuracy 1 nT; 2 = final data but no absolute measurements; 3 = preliminary data; 4 = data relative to quiet day night values. - Probable baseline change in 24 hours 2 in 0.1 nT - Components 1 1 = X,Y,Z; 2 = H,D (0.1'),Z; 3 = A,B,Z. - Character of day 1 0 = normal, 1 = one of the 5 inter- national quietest days; 2 = one of the 5 international most disturbed days. - Free 85 - X1,Y1,Z1 7 x 180 values in 0.1 nT units (0.1' if D). X2,Y2,Z2 The first character at left is the . sign, which is a space for positive . values and minus for negative values. X60,Y60,Z60 - Hourly mean of X 7 000000 if not the last part of hour - Hourly mean of Y 7 000000 if not the last part of hour - Hourly mean of Z 7 000000 if not the last part of hour The value for an interval is its mean. For example the value of the first minute of an hour is the mean value from XXh 00 min 00 s to XXh 01 min 00 s, etc. The values are given in units 0.1 nT. One record contains 1440 characters. Missing values are marked 999999. For merged tapes the stations follow each other by record. Leading zeros have to be used for fields that are too long. One record = one hour in the case of one-minute values, or part of an hour in the case of denser values. CODE : ASCII.