Definition of symbols:
- UMAGF comes from MAGnetic activity, code F
- I I I I I = station indicator
- Y = last digit of year
- MM = month of year, 01 = January, 02 = February, etc
- . DD = UT day of month
- HHmm = UT time in hour and minute
- / = filler
- DD = UT day of beginning 24-hour period reported
- HH = UT hour of beginning 24-hour period reported
- a = last digit of check sum of the Ak (bbb) and the 8 Ks.
- 1 = indicator for Ak index
- bbb = Ak index for UT date If Ak is not available, use ///
- 2 = indicator Ak index
- kkkk = first 4 K index
- 3 = indicator for last 4 k indices
- kkkk = last 4 K index
- c = indicator telling the time reported in HHmm is
- 1 = storm end
- 2 = bay (psc)
- 3 = ty../../pical crochet
- 4 = provisional figures
- 6 = gradual storm beginning
- 7 = sudden storm beginning
- 8 = very marked sudden storm beginning
- 9 = sudden impulse
- HHmm = UT hour and minute of phenomenon indicated by c.
If c=4, HHmm is used for reporting up to four additional K indices (3-hour periods) following the 24-hour interval reported by the 2 and 3 groups.
- 5 = signifies the following time refers to absolute value of minimum reached on the horizontal component
- HHmm = UT hour and minute of minimum
Note: Omit dHHMM group if data not available
- e e e e e = intensity of minimum expressed in nT
Note: Omit group e e e e e if these measurements are not made.
Note: / is to be used for data not available.