-message, @kbd{u} undeletes, and @kbd{x} expunges. @kbd{o} and @kbd{C-o}
-output the current message to a file; @kbd{r} starts a reply to it. You
-can scroll the current message while remaining in the summary buffer
-using @key{SPC} and @key{DEL}.
+message, @kbd{u} undeletes, and @kbd{x} expunges. (However, in the
+summary buffer, a numeric argument to @kbd{d}, @kbd{C-d} and @kbd{u}
+serves as a repeat count. A negative argument reverses the meaning of
+@kbd{d} and @kbd{C-d}.) @kbd{o} and @kbd{C-o} output the current
+message to a file; @kbd{r} starts a reply to it. You can scroll the
+current message while remaining in the summary buffer using @key{SPC}
+and @key{DEL}.