+extern unsigned tracing(void);
+
+/* --- @traceopt@ --- *
+ *
+ * Arguments: @trace_opt *t@ = pointer to trace options table
+ * @const char *p@ = option string supplied by user
+ * @unsigned f@ = initial tracing flags
+ * @unsigned bad@ = forbidden tracing flags
+ *
+ * Returns: Trace flags as set by user.
+ *
+ * Use: Parses an option string from the user and sets the
+ * appropriate trace flags. If the argument is null or a single
+ * `?' character, a help message is displayed.
+ */
+
+extern unsigned traceopt(trace_opt */*t*/, const char */*p*/,
+ unsigned /*f*/, unsigned /*bad*/);