@cindex abnormal hook
If the hook variable's name does not end with @samp{-hook}, that
-indicates it is probably an @dfn{abnormal hook}. That means one of
-two things: either that the hook functions are called with arguments,
-or that their return values are used in some way. The hook's
-documentation says how the functions are called. Any functions added
-to an abnormal hook must follow the hook's calling convention. By
-convention, abnormal hook names end in @samp{-functions}.
+indicates it is probably an @dfn{abnormal hook}. These differ from
+normal hooks in two ways: they can be called with one or more
+arguments, and their return values can be used in some way. The
+hook's documentation says how the functions are called and how their
+return values are used. Any functions added to an abnormal hook must
+follow the hook's calling convention. By convention, abnormal hook
+names end in @samp{-functions}.
@cindex single-function hook
If the name of the variable ends in @samp{-predicate} or