--- bison.texinfo	Thu Aug  9 12:01:35 2001
+++ bison.texinfo	Tue Aug  7 20:16:35 2001
@@ -2877,7 +2877,9 @@
 
 Though grammar rules and semantic actions are enough to write a fully
 functional parser, it can be useful to process some additionnal informations,
-especially locations of tokens and groupings.
+especially symbol locations.
+
address@hidden (terminal or not) ?
 
 The way locations are handled is defined by providing a data type, and actions
 to take when rules are matched.
@@ -2927,24 +2929,55 @@
 @code{@@@var{n}}, while the location of the left hand side grouping is
 @code{@@$}.
 
-Here is a simple example using the default data type for locations:
+Here is a basic example using the default data type for locations:
 
 @example
 @group
 exp:    @dots{}
-        | exp '+' exp
+        | exp '/' exp
             @{
+              @@$.first_column = @@1.first_column;
+              @@$.first_line = @@1.first_line;
               @@$.last_column = @@3.last_column;
               @@$.last_line = @@3.last_line;
-              $$ = $1 + $3;
+              if ($3)
+                $$ = $1 / $3;
+              else
+                @{
+                  $$ = 1;
+                  printf("Division by zero, l%d,c%d-l%d,c%d",
+                         @@3.first_line, @@3.first_column,
+                         @@3.last_line, @@3.last_column);
+                @}
             @}
 @end group
 @end example
 
address@hidden
-In the example above, there is no need to set the beginning of @code{@@$}. The
-output parser always sets @code{@@$} to @code{@@1} before executing the C
-code of a given action, whether you provide a processing for locations or not.
+As for semantic values, there is a default action for locations that is
+run each time a rule is matched. It sets the beginning of @code{@@$} to the
+beginning of the first symbol, and the end of @code{@@$} to the end of the
+last symbol. 
+
+With this default action, the location tracking can be fully automatic. The
+example above simply rewrites this way:
+
address@hidden
address@hidden
+exp:    @dots{}
+        | exp '/' exp
+            @{
+              if ($3)
+                $$ = $1 / $3;
+              else
+                @{
+                  $$ = 1;
+                  printf("Division by zero, l%d,c%d-l%d,c%d",
+                         @@3.first_line, @@3.first_column,
+                         @@3.last_line, @@3.last_column);
+                @}
+            @}
address@hidden group
address@hidden example
 
 @node Location Default Action,  , Actions and Locations, Locations
 @subsection Default Action for Locations
@@ -2952,34 +2985,43 @@
 
 Actually, actions are not the best place to compute locations. Since locations
 are much more general than semantic values, there is room in the output parser
-to define a default action to take for each rule. The @code{YYLLOC_DEFAULT}
-macro is called each time a rule is matched, before the associated action is
-run.
+to redefine the default action to take for each rule. The 
address@hidden macro is called each time a rule is matched, before the
+associated action is run. 
 
address@hidden Documentation for the old (?) YYLLOC_DEFAULT
+Most of the time, this macro is general enough to suppress location
+dedicated code from semantic actions. 
 
-This macro takes two parameters, the first one being the location of the
-grouping (the result of the computation), and the second one being the
-location of the last element matched. Of course, before @code{YYLLOC_DEFAULT}
-is run, the result is set to the location of the first component matched.
+The @code{YYLLOC_DEFAULT} macro takes three parameters. The first one is 
+the location of the grouping (the result of the computation). The second one 
+is an array holding locations of all right hand side elements of the rule 
+being matched. The last one is the size of the right hand side rule.
 
-By default, this macro computes a location that ranges from the beginning of
-the first element to the end of the last element. It is defined this way:
+By default, it is defined this way:
 
 @example
 @group
-#define YYLLOC_DEFAULT(Current, Last)           \
-  Current.last_line     = Last.last_line;       \
-  Current.last_column   = Last.last_column;
+#define YYLLOC_DEFAULT(Current, Rhs, N)         \
+  Current.last_line   = Rhs[N].last_line;       \
+  Current.last_column = Rhs[N].last_column;
 @end group
 @end example
 
address@hidden not Documentation for the old (?) YYLLOC_DEFAULT
+When defining @code{YYLLOC_DEFAULT}, you should consider that:
 
address@hidden
address@hidden @bullet
address@hidden 
+All arguments are free of side-effects. However, only the first one (the
+result) should be modified by @code{YYLLOC_DEFAULT}.
+
address@hidden
+Before @code{YYLLOC_DEFAULT} is executed, the output parser sets @code{@@$}
+to @code{@@1}.
 
-Most of the time, the default action for locations is general enough to
-suppress location dedicated code from most actions.
address@hidden
+For consistency with semantic actions, valid indexes for the location array
+range from 1 to @var{n}.
address@hidden itemize
 
 @node Declarations, Multiple Parsers, Locations, Grammar File
 @section Bison Declarations
--- ChangeLog	Thu Aug  9 12:16:22 2001
+++ ChangeLog	Thu Aug  9 12:21:43 2001
@@ -1,3 +1,7 @@
+2001-08-09  Robert Anisko  <address@hidden>
+
+	* doc/bison.texinfo (Locations): Update @$ stuff.
+
 2001-08-08  Marc Autret  <address@hidden>
 
 	* doc/bison.texinfo: Change @samp{$<@dots{}>} to