proc format ;
   value STAGET /* tumor size */
      0 = 'small'  
      1 = 'large' ;
   value STAGEN /* stage of nodes */
      0 = 'early'  
      1 = 'late' ;
   value HIST /* histology */
      1 = 'squamous cells'  
      2 = 'other types of cells' ;
   value TREAT /* treatment */
      0 = 'saline (control)'  
      1 = 'BCG (experiment)' ;
   value PERFBL /* perfomance status at baseline */
      0 = 'good'  
      1 = 'poor' ;
   value POINF /* post-operative infection */
      0 = 'no'  
      1 = 'yes' ;
   value SMOKFU /* smoking status at follow-up */
      1 = 'smokers'  
      2 = 'ex-smokers'  
      3 = 'never smokers' ;
   value SMOKBL /* smoking status at baseline */
      1 = 'smokers'  
      2 = 'ex-smokers'  
      3 = 'never smokers' ;
   value DEATH /* status at end of observation time */
      0 = 'alive (censored)'  
      1 = 'dead' ;
run;

/*
proc datasets ;
modify surv;
   format    STAGET STAGET.;
   format    STAGEN STAGEN.;
   format      HIST HIST.;
   format     TREAT TREAT.;
   format    PERFBL PERFBL.;
   format     POINF POINF.;
   format    SMOKFU SMOKFU.;
   format    SMOKBL SMOKBL.;
   format     DEATH DEATH.;
run;
quit;
*/