undocumented routine: CALL SOUND

I always keep an eye closely on SAS Samples, where I can get many interesting tips.

From this new sample, we can infer that CALL SOUND is another undocumented routine.
It will be a great way for reminder, not just in EG.

CALL SORTx routines

With CALL SORTx routines, we can sort and EXCHANGE the values of the variables. It is a very helpful since we need not assign a temporary variable for exchange of the values.
Below is an interesting sample code:

* Get the first two max height values;
data _null_;
  set sashelp.class end=last;
  retain max1 max2;

  call sortn(height, max2, max1);
  if last then put "max height value: " max1 max2;
run;