proc sort data=aaa;
by x1;
run;

proc sort data=bbb;
by x1;
run;

data wanted;
merge aaa bbb(rename=(line=line1));
  by x1;
  line=line1;
  drop line1;
run;

proc sort data=wanted;
by id line x1;
run;

data fmt;
set bbb;
retain fmtname '$x1fmt';
type='c';
rename x1=start line=label;
run;

proc format cntlin=fmt;
run;

data wanted;
set aaa;
line=put(x1,$x1fmt.)+0;
run;

不希望用format