Hi:
There's a difference between '' (quote quote) and ' ' (quote space quote) in the definition of a value to which a character format will apply. In addition with any user-defined format, you can use the keyword OTHER to "catch" all the values that do not fit into your categories.
The program below makes some data with missing values and bad values for the SEX variable from SASHELP.CLASS (using only a subset of rows). Consider the difference between using ' ' (quote space quote) in the format (report #1) and using OTHER in the format (report #2).
cynthia
[pre]
data class;
set sashelp.class;
if age = 11 then sex = ' ';
if age = 16 then sex = 'Z';
run;
proc format;
value $gend 'M' = 'Male'
'F' = 'Female'
' ' = 'Please Review';
value $altgend 'M' = 'Male'
'F' = 'Female'
other = 'Please Review';
run;
** only need to show a small subset;
proc sort data=class;
by sex;
where age in(11,12,16);
run;
proc print data=class;
format sex $gend.;
title '1 Using Space in format';
run;
proc print data=class;
format sex $altgend.;
title '2 Using OTHER in format';
run;
[/pre]