Some explanation about Area and Grap contour settings (From www.voacap.com by by Jari Perkiömäki)
Fact = multiplying factor

Usually either 1. or 100. (100 for percents)

Code = calculation code

0 = user-defined values given in CON(n) (max of 6 allowed)
1 = Automatic Max, down to manual MIN in DECR decrements
2 = Automatic generated/defined steps by program
3 = Automatic Min, up to manual MAX in INCR steps

Args = number of numeric arguments to follow.
Con(n) = numeric arguments, up to args
1: USER DEFINED CONTOUR VALUES (CODE = 0)

Param MUF days (MUFday= % of days/month sky-wave propagation expected at MUF mode)
Factor 100.
Code 0: user specified
Args 6
Con(1) 1.
Con(2) 10.
Con(3) 50.
Con(4) 90.
Con(5) 99.
Con(6) 110.
Explanations:
Multiply values in datafile by 100.
Use 6 values given.
2: PROGRAM DEFINES MAX TO USER DEFINED MIN + DECREMENT (CODE = 1)
Param DBU (Median field strength at receive location (dBu))
Factor 1.
Code 1: find max go min
Args 2
Decr 5.
Min. 0.
Explanations:
Find MAX in datafile (e.g. say it was 69)
Round up to the next multiple of CON(1) (70 in this case).
Contours start at 70 (but you will not see this one) and go down in steps of 5 [= CON(1)] for 6 contours. The lower limit will be 0 [= CON(2)]. Thus, if max was 14, contours would be >10, 5, <0.
3. PROGRAM DEFINED MAX, MIN AND INCREMENT (CODE = 2)
Param TANGLE (Radiation angle (degrees))
Factor 1.
Code 2: automatic
Args 0
Explanations:
Find MIN and MAX in datafile (e.g. 4.6, 32.3)
The steps are based on a complicated algorithm, but it essentially finds 6 contours within the min and max. In this case it would find <6,12,18,24,30,>30.
4. PROGRAM DEFINED MIN TO USER DEFINED MAX AND INCREMENT (CODE = 3)
Param RPWRG (Required power & antenna gain to achieve reliab (dB))
Factor 1.
Code 3: find min go max
Args 2
Incr 10.
Max 200.
Explanations:
Find MIN in datafile
Round down to the next multiple of CON(1)
Contours start at this value and go up in steps of 10 [= CON(1)] for 6 contours. The upper limit is 200 [= CON(2)].
code=3 is opposite of code=1, and is used for values that are really negative, but are calculated as positive values (such as LOSS & RPWRG).
See also: Point-to-Point Time- and Distance Y-axis scaling