+ The strings returned by <STRONG>unctrl</STRONG> in this implementation are
+ determined at compile time, showing C1 controls from the
+ upper-128 codes with a `~' prefix rather than `^'. Other
+ implementations typically show both sets of control char-
+ acters with `^', and may strip the parameter to 7 bits.
+ This implementation uses 8 bits but does not modify the
+ string to reflect locale.