使用compress函数，compress(variable,"","modifier")，modifier可以使用k，表示保留，用d表示数字，kd表示只保留数字
如level=compress(course,"","kd");
同样有一个modifier表示字母，具体我忘了，你可以查一下，
要么就是subj=compress(course,"0123456789");

level=substr(course,length(course)-2,3);
SUBJECT=substr(course,1,length(course)-3);

IMASASOR说的应该是这个。

It is better to use function to identify the positions and handle it accordingly. Keep in mind to minimize the assumptions about data structures.

data def;
length subject level $15;
input x $20.;
subject=substr(x,1,indexc(x,'0123456789')-1) ;
level  =substr(x,indexc(x,'0123456789')) ;
cards;
HIST400
SCI400
MATH400
HIST400
LANGUAGE12345
;

proc print;run;

compress(character-value,<,'compress-list'>,<,modifiers>)
其中modifiers有：
a include all upper and lowercase letter
d include all digits
i ignore the case of character
还有 k p s