Professional SAS Programming Secrets

*
  Professional SAS Programming Secrets
  Program 5d
  Special values in value informats
*;
proc format;
invalue m99m (min=1 max=32 upcase just)
    -99 = .
    other = _same_;
invalue gp (min=1 max=32 upcase just)
    'F' = 0  'D' = 1  'C' = 2  'B' = 3  'A' = 4  ' ' = .  other = _error_;
invalue month (min=3 max=32 upcase just)
    1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 = _same_   0, ' ' = .
    'JAN', 'JANUARY' = 1   'FEB', 'FEBRUARY' = 2   'MAR', 'MARCH' = 3
    'APR', 'APRIL' = 4   'MAY' = 5   'JUN', 'JUNE' = 6   'JUL', 'JULY' = 7
    'AUG', 'AUGUST' = 8   'SEP', 'SEPTEMBER' = 9   'OCT', 'OCTOBER' = 10
    'NOV', 'NOVEMBER' = 11   'DEC', 'DECEMBER' = 12   other = _error_;
run;