David,
 
If you are writing in HP C, don't forget
 
#pragma intrinsic HPCIPUTVAR
 
!!!
 
Here is a code snippet from a test program:
 
#pragma intrinsic HPCIPUTVAR
/*-------------------------------------------------------------------------*/
/* this procedure is called by test programs. it calls HPCIPUTVAR to set   */
/* CI variable to the passed int value.                                    */
/*-------------------------------------------------------------------------*/
void Put_Int_Var(char *varname, int value)
  {                                                   /* Put_Int_Var */
     hpe_status  status;
     unsigned keyword;
     int keyvalue;
 
     keyword = 1;                     /* integer value to be assigned */
     keyvalue = value;
 
     HPCIPUTVAR(varname, &status, keyword, &keyvalue);
 
     if (status.all != 0)
        log_err_status("HPCIPUTVAR in Put_Int_Var", status);
  }                                                   /* Put_Int_V */
 
Put_Int_Var("PPXES10N", 127);
 
Steve