Document the new prefix-command hooks

* doc/lispref/hooks.texi (Standard Hooks): Document
`prefix-command-echo-keystrokes-functions' and
`prefix-command-preserve-state-hook'.

1 files changed, 16 insertions, 0 deletions

diff --git a/doc/lispref/hooks.texi b/doc/lispref/hooks.texi
index cbbaa8e5ea0..b8f761de30e 100644
--- a/doc/lispref/hooks.texi
+++ b/doc/lispref/hooks.texi
@@ -190,6 +190,22 @@ Hook run when about to switch windows with a mouse command.
 @item post-self-insert-hook
 @xref{Keymaps and Minor Modes}.
 
+@item prefix-command-echo-keystrokes-functions
+@vindex prefix-command-echo-keystrokes-functions
+An abnormal hook run by prefix commands (such as @kbd{C-u}) which
+should return a string describing the current prefix state.  For
+example, @kbd{C-u} produces @samp{C-u-} and @samp{C-u 1 2 3-}.  Each
+hook function is called with no arguments and should return a string
+describing the current prefix state, or @code{nil} if there's no
+prefix state.  @xref{Prefix Command Arguments}.
+
+@item prefix-command-preserve-state-hook
+@vindex prefix-command-preserve-state-hook
+Hook run when a prefix command needs to preserve the prefix by passing
+the current prefix command state to the next command.  For example,
+@kbd{C-u} needs to pass the state to the next command when the user
+types @kbd{C-u -} or follows @kbd{C-u} with a digit.
+
 @ignore
 @item prog-mode-hook
 @itemx special-mode-hook