-Values above 128 are either meta characters, shown in the \fBM-\fR\fIX\fR notation,
-or the names of function keys, or null.
+.TP 3
+-
+DEL (character 127) is displayed as \fB^?\fP.
+.TP 3
+-
+Values above 128 are either meta characters
+(if the screen has not been initialized,
+or if \fBmeta\fP has been called with a TRUE parameter),
+shown in the \fBM-\fR\fIX\fR notation,
+or are displayed as themselves.
+In the latter case, the values may not be printable;
+this follows the X/Open specification.
+.TP 3
+-
+Values above 256 may be the names of the names of function keys.
+.TP 3
+-
+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.
+.RE
+.LP