~ chicken-core (chicken-5) f7cf41912e6cf4c28402f98bd5c7e3de02e59084

commit f7cf41912e6cf4c28402f98bd5c7e3de02e59084
Author:     Jim Ursetto <zbigniewsz@gmail.com>
AuthorDate: Tue Jan 29 14:35:35 2013 -0600
Commit:     Jim Ursetto <zbigniewsz@gmail.com>
CommitDate: Tue Jan 29 14:35:35 2013 -0600

    manual: note set-read-syntax! can return zero values, from way back in c1dc721cd9

diff --git a/manual/Unit library b/manual/Unit library
index 232d42c9..86f92f78 100644
--- a/manual/Unit library	
+++ b/manual/Unit library	
@@ -1204,15 +1204,16 @@ to the reader:
 
 If {{CHAR-OR-SYMBOL}} is a symbol, then a so-called ''read-mark'' handler is defined.
 In that case the handler procedure will be called when a character-sequence of the
-form
-
- #!SYMBOL
-
-is encountered.
+form {{#!SYMBOL}} is encountered.
 
 You can undo special handling of read-syntax by passing {{#f}} as the second argument
 (if the syntax was previously defined via {{set-read-syntax!}}).
 
+As a special case, your handler can return zero values, via {{(values)}}.  This causes
+the reader to completely ignore whatever input you've read, rather than returning some
+possibly unspecified value.  This can be useful in macro context, reading comments,
+conditional compilation, and so forth.  Available in Chicken 4.6.6 and later.
+
 Note that all of CHICKEN's special non-standard read-syntax is handled directly by the reader.
 To disable built-in read-syntax, define a handler that triggers an error (for example).