-An association list describing new bindings for special variables
-(typically *PRINT-FOO* variables) to be used within the debugger, e.g.
-@lisp
-((*PRINT-LENGTH* . 10) (*PRINT-LEVEL* . 6) (*PRINT-PRETTY* . NIL))
-@end lisp
-The variables in the @code{car} position are bound to the values in
-the @code{cdr} during the execution of some debug commands. When
-evaluating arbitrary expressions in the debugger, the normal values of
-the printer control variables are in effect. @c FIXME: is this correct?
-@code{*debug-print-variable-alist*} does not contain any bindings
-initially.
+When the debugger is invoked by a condition, ANSI mandates that the
+value of @code{*debugger-hook*}, if any, be called with two arguments:
+the condition that caused the debugger to be invoked and the previous
+value of @code{*debugger-hook*}. When this happens,
+@code{*debugger-hook*} is bound to NIL to prevent recursive errors.
+However, ANSI also mandates that @code{*debugger-hook*} not be invoked
+when the debugger is to be entered by the @code{break} function. For
+users who wish to provide an alternate debugger interface (and thus
+catch @code{break} entries into the debugger), SBCL provides
+@code{sb-ext:*invoke-debugger-hook*}, which is invoked during any
+entry into the debugger.
+
+@include var-sb-ext-star-invoke-debugger-hook-star.texinfo
+
+@node Debugger Command Loop
+@comment node-name, next, previous, up
+@section Debugger Command Loop
+
+The debugger is an interactive read-eval-print loop much like the
+normal top level, but some symbols are interpreted as debugger
+commands instead of being evaluated. A debugger command starts with
+the symbol name of the command, possibly followed by some arguments on
+the same line. Some commands prompt for additional input. Debugger
+commands can be abbreviated by any unambiguous prefix: @command{help}
+can be typed as @samp{h}, @samp{he}, etc.
+
+The package is not significant in debugger commands; any symbol with
+the name of a debugger command will work. If you want to show the
+value of a variable that happens also to be the name of a debugger
+command you can wrap the variable in a @code{progn} to hide it from
+the command loop.
+
+The debugger prompt is ``@code{@var{frame}]}'', where @var{frame} is
+the number of the current frame. Frames are numbered starting from
+zero at the top (most recent call), increasing down to the bottom.
+The current frame is the frame that commands refer to.
+
+It is possible to override the normal printing behaviour in the
+debugger by using the @code{sb-ext:*debug-print-variable-alist*}.