proc format; 
value who_cat2_f	1='Mild/Moderate'
					2='Very Severe'; 

value positive_f	0='Negative'
					1='Positive';

value retinopathy_f 0='No Retinopathy'	
					1='Retinopathy';

value sex_f	1='Female' 
			2='Male';

value check_f	0='Unchecked'
				1='Checked';

value yesno_f	0='No'
				1='Yes'
				2='No';

value race_f	1='Asain'
				2='Black'
				3='White'
				4='Unknown';
run;