+/*
+ * UCSWIDE is a special value used in the terminal data to signify
+ * the character cell containing the right-hand half of a CJK wide
+ * character. We use 0xDFFF because it's part of the surrogate
+ * range and hence won't be used for anything else (it's impossible
+ * to input it via UTF-8 because our UTF-8 decoder correctly
+ * rejects surrogates).
+ */
+#define UCSWIDE 0xDFFF