1 files changed, 18 insertions, 17 deletions

diff --git a/lispref/debugging.texi b/lispref/debugging.texi
index 07dfe18f283..739dd1fe298 100644
--- a/lispref/debugging.texi
+++ b/lispref/debugging.texi
@@ -118,8 +118,8 @@ the error.  The easiest way is usually to set
 @end defopt
 
 @defopt eval-expression-debug-on-error
-If you set this variable to a non-@code{nil} value, then
-@code{debug-on-error} will be set to @code{t} when evaluating with the
+If this variable has a non-@code{nil} value, then
+@code{debug-on-error} is set to @code{t} when evaluating with the
 command @code{eval-expression}.  If
 @code{eval-expression-debug-on-error} is @code{nil}, then the value of
 @code{debug-on-error} is not changed.  @xref{Lisp Eval,, Evaluating
@@ -210,15 +210,19 @@ called shortly before the problem, step quickly over the call to that
 function, and then step through its caller.
 
 @deffn Command debug-on-entry function-name
-This function requests @var{function-name} to invoke the debugger each time
-it is called.  It works by inserting the form @code{(debug 'debug)} into
-the function definition as the first form.
-
-Any function defined as Lisp code may be set to break on entry,
-regardless of whether it is interpreted code or compiled code.  If the
-function is a command, it will enter the debugger when called from Lisp
-and when called interactively (after the reading of the arguments).  You
-can't debug primitive functions (i.e., those written in C) this way.
+This function requests @var{function-name} to invoke the debugger each
+time it is called.  It works by inserting the form
+@code{(implement-debug-on-entry)} into the function definition as the
+first form.
+
+Any function or macro defined as Lisp code may be set to break on
+entry, regardless of whether it is interpreted code or compiled code.
+If the function is a command, it will enter the debugger when called
+from Lisp and when called interactively (after the reading of the
+arguments).  You can also set debug-on-entry for primitive functions
+(i.e., those written in C) this way, but it only takes effect when the
+primitive is called from Lisp code.  Debug-on-entry is not allowed for
+special forms.
 
 When @code{debug-on-entry} is called interactively, it prompts for
 @var{function-name} in the minibuffer.  If the function is already set
@@ -267,16 +271,13 @@ Debugger entered--entering a function:
 @end example
 @end deffn
 
-@deffn Command cancel-debug-on-entry function-name
+@deffn Command cancel-debug-on-entry &optional function-name
 This function undoes the effect of @code{debug-on-entry} on
 @var{function-name}.  When called interactively, it prompts for
 @var{function-name} in the minibuffer.  If @var{function-name} is
-@code{nil} or the empty string, it cancels break-on-entry for all
-functions.
-
+omitted or @code{nil}, it cancels break-on-entry for all functions.
 Calling @code{cancel-debug-on-entry} does nothing to a function which is
-not currently set up to break on entry.  It always returns
-@var{function-name}.
+not currently set up to break on entry.
 @end deffn
 
 @node Explicit Debug