Your program does not have an input statement. Instead you have an assignment state where the value being assigned is the result of the INPUT() function.  It is not clear what editor you are using, but the SAS Display Manager's "enchanced" editor does not color code function names.    You INPUT function call is just taking the first three characters from the variable HIVYEARS.  The $ informat simply converts text into text. It would be clearer to use the substr() function (or the newer substrn() function). hiv_years = substr(hivyears,1,3);   ... View more