请问，在哪里可以找到kad及相关的参数？

在sas的support中也没有查到。。谢谢

You could find information on findc function at:
https://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a002264923.htm

In addition, here is method to find punctuation position with prx.

data have;
input x$ ;
pos=findc(x,'_ ','kad');
prx_pos=prxmatch('/[^a-z0-9_]/',strip(x));
cards;
34jfk
_e35&
%7yud_u
1a34_6|89
;
run;

明白你要做什么了，感觉不太可能把这两件事情放在一个 prx-pattern.

Not sure whether the following is the same as your case. But you have many ways to do it with two patterns.

data _null_;
if _n_ = 1 then do;
     pn1="/[[:punct:]]/";      p1 = prxparse(pn1);
         pn2="/[_]/";               p2=prxparse(pn2);
         retain p1 p2;
end;
input string $10.;
    position1 = prxmatch(p1, string);  
    position2 = prxmatch(p2, string);  
    if position1 = position2 then
put _n_=   "the first punctuation is found     to be an _ at position: " position1 " in string: " string;
    if position1 ^= position2 then
put _n_= "the first punctuation is found not to be an _ at position: " position1 " in string: " string;
datalines;
1234__&*=_
1234*:'_?_
^~!',:"??_
_~!',:"??_
; run;