detect UTF-16 surrogates as bad, use red for overlong

1 files changed, 10 insertions, 6 deletions

diff --git a/uxd.rst b/uxd.rst
index 535177d..1789efe 100644
--- a/uxd.rst
+++ b/uxd.rst
@@ -234,14 +234,10 @@ changed with the **-c** option (see above).
   dumpers do. The Unicode BOM (byte order marker, U+FEFF) is printed
   as a purple letter B.
 
-  Note: Overlong encodings (e.g. codepoints U+0000 to U+007F encoded
-  as 2 or more bytes) are rendered as � (U+0FFD) in reverse video
-  purple.
-
 **red**
   Invalid UTF-8 sequences. These are rendered as � (U+0FFD) with
-  a red background, to make them stand out. Examples of invalid
-  sequences:
+  a red background, to make them stand out. Invalid
+  sequences are:
 
     - Prefix bytes (>= 0x80) which are not followed by the correct number of continuation
       bytes (with their high 2 bits set to **10**).
@@ -250,8 +246,16 @@ changed with the **-c** option (see above).
 
     - Truncated UTF-8 sequence at EOF.
 
+    - UTF-16 surrogates (codepoints U+D800 to U+DFFF).
+
     - Codepoints above U+10FFFF, which are disallowed by RFC 3629.
 
+    - Overlong encodings (e.g. codepoints U+0000 to U+007F encoded
+      as 2 or more bytes).
+
+    Each occurrence of any of the above will increment the "Bad
+    Sequences" count, if the **-i** option is used.
+
 TERMINAL SUPPORT
 ================