The data format in these files changes slightly at years 1977 and 1982.
The format is given below.

Columns Quantity
1-4     Year
5-6     Month
7-8     Day of month
9-12    Time in thousandths of day (.500 = 1200 UT)
13-20   Greenwich sunspot group # through 1976; NOAA/USAF grp # after 1976

21-22   00 1874-1981
23-24   Greenwich Group type

21      Suffix to group number 1982 to present
22-24   Magnetic group type (A=Alpha, B=Beta, D=Delta, G=Gamma) 1982 to present

25      Single space
26-29   Observed umbral area in millionths of solar disk 1874 through 1981

26-29   Zurich/McIntosh group type from 1982 to present (umbral area unavailable from NOAA)

30      Single space
31-34   Observed whole spot area in mill. of sol. disk
35      Single space
36-39   Corrected (for foreshortening) umbral area in millionths of solar
        hemisphere, 1874 through 1981

36-39   Number of spots in group from 1982 to present (umbral area unavailable from NOAA)

40      Single space
41-44   Corrected whole spot area in millionths of solar hemisphere
45      Single space
46-50   Distance from center of solar disk in disk radii
51      Single space
52-56   Position angle from heliographic north (0=north, 90=east limb)
57      Single space
58-62   Carrington Longitude in degrees
63      Single space
64-68   Latitude, negative to the South
69      Single space
70-74   Central  meridian distance, negative to the East.