/* these IN and OUT filerefs can point to anything */
filename in "anyfilehere.xlsx"; 
filename out "anyfilehere.xlsx"; 
/* copy the file byte-for-byte  */
data _null_;
  length filein 8 fileid 8;
  filein = fopen('in','I',1,'B');
  fileid = fopen('out','O',1,'B');
  ...