Email class: adjust documentation and make the code backward compatible
diff --git a/system/libraries/Email.php b/system/libraries/Email.php
index df03eaa..7320ea5 100644
--- a/system/libraries/Email.php
+++ b/system/libraries/Email.php
@@ -408,10 +408,10 @@
 	 * @param	string
 	 * @return	object
 	 */
-	public function attach($filename, $str = '', $mime = '', $disposition = '', $newname = NULL)
+	public function attach($filename, $disposition = '', $str = '', $mime = '', $newname = NULL)
 	{
 		$this->_attach_name[] = array($filename, $newname);
-		$this->_attach_type[] = ($mime === '') ? $this->_mime_types(pathinfo($filename, PATHINFO_EXTENSION)) : $mime;
+		$this->_attach_type[] = ($mime == '') ? $this->_mime_types(pathinfo($filename, PATHINFO_EXTENSION)) : $mime;
 		$this->_attach_disp[] = empty($disposition) ? 'attachment' : $disposition; // Can also be 'inline'  Not sure if it matters
 		$this->_attach_content[] = $str;
 		return $this;
diff --git a/user_guide_src/source/libraries/email.rst b/user_guide_src/source/libraries/email.rst
index d05439a..2be50fd 100644
--- a/user_guide_src/source/libraries/email.rst
+++ b/user_guide_src/source/libraries/email.rst
@@ -228,19 +228,18 @@
 	$this->email->attach('/path/to/photo2.jpg');
 	$this->email->attach('/path/to/photo3.jpg');
 
-$filename, $str = '', $mime = '', $disposition = '', $newname = NULL
+To use the default disposition (attachment), leave the second parameter blank.
 If you need to use a buffer string instead of a real (physical) file you can use the
-second and third parameters that are respectively the buffer and the mime-type::
+third and fourth parameters that are respectively the buffer and the mime-type::
 
-	$this->email->attach('report.pdf', $buffer, 'application/pdf');
+	$this->email->attach('report.pdf', 'inline', $buffer, 'application/pdf');
 
-If you'd like to change the disposition or add a custom file name, you can use the 
-fourth and fifth paramaters. To use the default disposition (attachment), leave the 
-fourth parameter blank. Here's an example::
+If you'd like to add a custom file name, you can use the fifth paramaters.
+Here's an example::
   
-	$this->email->attach('/path/to/photo1.jpg', '', '', 'inline');
+	$this->email->attach('/path/to/photo1.jpg', '', '', '', 'inline');
 	$this->email->attach('/path/to/photo1.jpg', '', '', '', 'birthday.jpg');
-	
+
 
 $this->email->print_debugger()
 -------------------------------