LIMITATIONS AND ASSUMPTIONS The restrictions as well as the principles taken for granted in using the DVAL program areas follows: l The algorithm used by this program applies to a maximum  altitude  of  11,000  geopotential  meters. .  The  D-value  for  MSL  is  determined  by extrapolating the pressure and temperature data to MSL by using the data for the first two levels of the entered environmental  profile.  Caution  should  be  exercised  in determining  over-water  surface  D-values  using radiosonde  data  from  a  coastal  location  when  the balloon-release height is >50 meters. FUNCTIONAL  DESCRIPTION AD-value is defined as a difference in the observed height of a particular isobaric surface and the height associated  with  that  isobaric  surface  in  the  U.S. Standard Atmosphere. Table 7-1 shows an example of the D-value profile. Table 7-1.-Example Output of the D-Value Profile UNCLASSIFIED D-VALUE   PROFILE ALT.(F) D-VALUE(F) ALT.(F) D-VALUE(F) ALT.(F) D-VALUE(F) .0 1.4 9500.0 28.8 19000.0 42.4 500.0 3.1 10000.0 29.7 19500.0 43.1 1000.0 4.8 10500.0 30.1 20000.0 44.0 1500.0 6.6 11000.0 30.6 20500.0 45.0 2000.0 8.3 11500.0 31.0 21000.0 46.1 2500.0 10.1 12000.0 31.5 21500.0 47.4 3000.0 11.9 12500.0 32.0 22000.0 48.9 3500.0 13.7 13000.0 32.6 22500.0 50.5 4000.0 15.5 13500.0 33.2 23000.0 52.3 4500.0 17.4 14000.0 33.8 23500.0 54.2 5000.0 18.9 14500.0 34.5 24000.0 56.1 5500.0 20.1 15000.0 35.2 24500.0 57.8 6000.0 21.2 15500.0 36.0 25000.0 59.4 6500.0 22.2 16000.0 36.9 25500.0 61.0 7000.0 23.3 16500.0 37.8 26000.0 62.5 7500.0 24.4 17000.0 38.8 26500.0 63.9 8000.0 25.5 17500.0 39.8 27000.0 65.2 8500.0 26.6 18000.0 40.9 27500.0 66.4 9000.0 27.7 18500.0 41.8 28000.0 67.6 171255  UTC  AUG86  3500N  01500E UNCLASSIFIED 7-3