/VALID=(val1,val2...)

   Getinput can compare the user input to valid possibilities specified
   with /VALID.

   Options are:

   /VALID=(str1,str2,str3)       As user input only the valid
                                 strings are accepted. When the
                                 user input is unique, only the
                                 unique part is needed, see examples.
   /VALID=(2,4,6)                As user input only the strings
                                 2, 4 and 6 are accepted.
   /VALID=(1,10)                 As user input only the strings
                                 1 and 10 are accepted.
   /VALID=(1,10)/TYPE=INTEGER    As user input an integer from
                                 1 to 10 is accepted.
   /VALID=(1,10)/TYPE=INT/NORANG As user input the integers 1 and 10
                                 are accepted.