すべての文字を小文字にする
LOWCASE関数
str = lowcase('INTRODUCTION');
...
https://documentation.sas.com/doc/ja/pgmsascdc/v_061/ds2ref/n0mwurvelifv54n18gbah5nmefn5.htm
str = lowcase('INTRODUCTION');
...
https://documentation.sas.com/doc/ja/pgmsascdc/v_061/ds2ref/n0mwurvelifv54n18gbah5nmefn5.htm