-# Ignore log entries that start with `#'.
-# Clump together log entries that start with `{topic} ',
-# where `topic' contains neither white space nor `}'.
+Generate entries for changes entered into RCS (or CVS) more recently
+than the newest existing entry in the ChangeLog file. You can then
+edit these entries by hand, and prepend them to the ChangeLog file.
+
+Output the resulting ChangeLog entries to standard output.
+Each entry looks something like this:
+
+2004-04-17 Paul Eggert <eggert@gnu.org>
+
+ * rcs2log (Help): Clarify wording of the usage message.
+ Problem reported by Alan Mackenzie in
+ <http://mail.gnu.org/archive/html/bug-gnu-emacs/2004-04/msg00188.html>.
+
+ChangeLog entries contain the current date, full name, email address
+including hostname, the name of the affected file, and commentary.
+RCS and CVS logs lack full names and email addresses, so they are
+inferred from login names using a heuristic that can be overridden
+via the -u option.
+
+Ignore log entries that start with "#".
+Clump together log entries that start with "{topic} ",
+where "topic" contains neither white space nor "}".
+
+If no FILE is specified, use all files under the working directory
+that are maintained under version control.