Looks like a normal IF THEN statement. SAS does support using | and & as substitutes of AND and OR, but I can never remember which is which so it is probably better use the human readable keywords instead.
And IF statement would need to be part of a DATA step. So if you have a dataset named HAVE that has the I3 and I3_1 variables then you could use a step like this to make a dataset named WANT that adds the I3_UNMET variable.
data want;
set have;
IF (i3=0 or i3_1=2) then i3_unmet=0 ;
IF (i3_1=0 or i3_1=1) then i3_unmet=1 ;
run;
For other combinations of values of i3 and i3_1 (such as when i3=1 or when i3_1=4) the value of I3_UNMET will not be set.
So if it already exists in the HAVE dataset the value for those observations will be unchanged.
And if it was not in the HAVE dataset then the value will be missing.