** SAS Code for Time To / From Surgery  ;
array ops(# of procedure) first procedure code - last procedure code; 
||array sdate(12) 1st surgery date - last surgery date; 
|| 
||do i=1 to 12 while (ops{i} ne ' '); 
||    if (put(ops{i},$hipopf.)) then do; 
|| 
||        if sdate{i}>'0' then surgdate=input(put(sdate{i},6.),yymmdd6.); 
||        else surgdate=input(dateadm,yymmdd6.); 
||   end; 
||end;