diff --git a/doc/sources/admin/exportedvars.rst b/doc/sources/admin/exportedvars.rst
index 606ada20b..3f0354e7b 100644
--- a/doc/sources/admin/exportedvars.rst
+++ b/doc/sources/admin/exportedvars.rst
@@ -10,7 +10,7 @@ extracted from the users database by the
 :ref:`users module<start-authentication-users-and-password-databases>`.
 
 To create a variable, you've just to map a user attributes in LL::NG
-using ``Variables`` » ``Exported variables``. For each variable, The
+using ``Variables`` » ``Exported variables``. For each variable, the
 first field is the name which will be used in rules, macros or headers
 and the second field is the name of the user database field.
 
diff --git a/doc/sources/admin/rules_examples.rst b/doc/sources/admin/rules_examples.rst
index 2bd7dd396..a65f50310 100644
--- a/doc/sources/admin/rules_examples.rst
+++ b/doc/sources/admin/rules_examples.rst
@@ -27,6 +27,16 @@ attribute you see there can be used in a rule!
     In Perl, ``eq`` means *Equal* and must be used on strings.
     ``==`` should be used only on numbers
 
+.. danger::
+
+    In Perl, ``@`` character means an array and ``%`` a hash!
+    If you want to write a macro with these characters, you have to escape them like this:
+
+::
+
+    $my_email = "$uid\@my-domain.com"
+    $percent = "$rate\%more"
+
 -  Restricting access to specific groups
 
 ::
diff --git a/doc/sources/admin/writingrulesand_headers.rst b/doc/sources/admin/writingrulesand_headers.rst
index 5e3e427df..4b1ff8c17 100644
--- a/doc/sources/admin/writingrulesand_headers.rst
+++ b/doc/sources/admin/writingrulesand_headers.rst
@@ -173,14 +173,14 @@ use macros, local macros,...
 
 .. attention::
 
-
-
     -  Since many HTTP servers refuse non ascii headers, it is recommended
        to use encode_base64() function to transmit those headers
     -  Don't forget to add an empty string as second argument to
        encode_base64 function to avoid a "newline" characters insertion in
        result
-    -  Header names must contain only letters and "-" character
+    -  Header names must contain only letters and "-" character.
+       With Nginx, you can bypass this restriction by using
+       ``underscores_in_headers on;`` directive