diff --git a/doc/hook/modify_command b/doc/hook/modify_command
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+++ b/doc/hook/modify_command
@@ -0,0 +1,61 @@
+SYNOPSIS
+        #include <sys/driver_hooks.h>
+
+        set_driver_hook(H_MODIFY_COMMAND, value)
+
+        <value> being:
+
+          int|string <closure>(string cmd, object player)
+          int|string <name>(string cmd)
+          <mapping>
+
+DESCRIPTION
+        Optional hook to modify commands (both entered or given by a
+        call to command()) before the parser sees them (this includes
+        special commands like 'status').
+
+        Hook setting can be any closure, the name of the function to
+        call in the object, or a mapping.
+
+        For interactives this hook is used only if the interactive
+        object has no command modifier already set by the efun
+        set_modify_command().
+
+        If the hook is a closure, it is called with the entered
+        command as first, and the command giving player as second
+        argument. Lambda closures are bound to the command giving player,
+        unbound-lambda closures remain unbound.
+
+        If the hook is a string, it is used as the name of an lfun
+        in the command giving player, which is called with the command
+        as argument.
+
+        If the hook is a mapping, it is queried with the given command
+        as index, and the data retrieved is used as new command
+        (defaults to 0 if no data is stored for a given command). If
+        an entry is a closure instead of a string, it is called as
+
+          int|string <closure>(string cmd, object player)
+
+        and the result from the call is used as 'the' command.
+
+        The result is treated equal in all three cases:
+         - If the result is a string, it is the new command to execute
+           instead of the given one. Note that it is not possible to
+           make several commands from one this way!
+         - If the result is a non-zero number, the given command is to
+           be ignored. In case of the closure/lfun setting this may
+           mean that the closure/lfun already executed it.
+         - If the result is 0, the originally given command is to be
+           used.
+
+        It is possible for the hook to change the command giver
+        (this_player()) for the execution of the command. This means that
+        even though the commands are execute for the original commandgiver,
+        this_player() will return the changed commandgiver.
+
+HISTORY
+
+SEE ALSO
+        hooks(C), command(H), modify_command_fname(H), notify_fail(H),
+        send_notify_fail(H)