- ing to the key <EM>c</EM>. Control characters are displayed in the
- <STRONG>^</STRONG><EM>X</EM> notation. Values above 128 are either meta characters,
- shown in the <STRONG>M-</STRONG><EM>X</EM> notation, or the names of function keys,
- or null. The corresponding <STRONG>key_name</STRONG> returns a character
- string corresponding to the wide-character value <EM>w</EM>. The
- two functions do not return the same set of strings; the
- latter returns null where the former would display a meta
- character.
+ ing to the key <EM>c</EM>:
+
+ - Printable characters are displayed as themselves,
+ e.g., a one-character string containing the key.
+
+ - Control characters are displayed in the <STRONG>^</STRONG><EM>X</EM> notation.
+
+ - DEL (character 127) is displayed as <STRONG>^?</STRONG>.
+
+ - Values above 128 are either meta characters (if the
+ screen has not been initialized, or if <STRONG>meta</STRONG> has been
+ called with a TRUE parameter), shown in the <STRONG>M-</STRONG><EM>X</EM> no-
+ tation, or are displayed as themselves. In the lat-
+ ter case, the values may not be printable; this fol-
+ lows the X/Open specification.
+
+ - Values above 256 may be the names of the names of
+ function keys.
+
+ - Otherwise (if there is no corresponding name) the
+ function returns null, to denote an error. X/Open
+ also lists an "UNKNOWN KEY" return value, which some
+ implementations return rather than null.
+
+ The corresponding <STRONG>key_name</STRONG> returns a character string cor-
+ responding to the wide-character value <EM>w</EM>. The two func-
+ tions do not return the same set of strings; the latter
+ returns null where the former would display a meta charac-
+ ter.