_CP_build_msg queues up arguments for _CP_out_msg. This function, in conjunction with _CP_out_msg, is equivalent to the BASIC error statement. Each parameter is first stacked with _CP_build_msg, and then output with the _CP_out_msg.
nt _CP_build_msg(CPSTR * s)
/* Print file not found message */
CPSTR * s = _CP_mkstr("201");
CPSTR * t = _CP_mkstr("myfile");
_CP_build_msg(s);
_CP_build_msg(t);
_CP_out_msg();