diff --git a/system/libraries/Form_validation.php b/system/libraries/Form_validation.php
index 0a6a2af..20f1faf 100644
--- a/system/libraries/Form_validation.php
+++ b/system/libraries/Form_validation.php
@@ -25,8 +25,6 @@
  * @filesource
  */
 
-// ------------------------------------------------------------------------
-
 /**
  * Form Validation Class
  *
@@ -48,9 +46,6 @@
 	protected $error_string			= '';
 	protected $_safe_form_data		= FALSE;
 
-	/**
-	 * Constructor
-	 */
 	public function __construct($rules = array())
 	{
 		$this->CI =& get_instance();
@@ -67,7 +62,7 @@
 			mb_internal_encoding($this->CI->config->item('charset'));
 		}
 
-		log_message('debug', "Form Validation Class Initialized");
+		log_message('debug', 'Form Validation Class Initialized');
 	}
 
 	// --------------------------------------------------------------------
@@ -179,7 +174,6 @@
 		}
 
 		$this->_error_messages = array_merge($this->_error_messages, $lang);
-
 		return $this;
 	}
 
@@ -198,7 +192,6 @@
 	{
 		$this->_error_prefix = $prefix;
 		$this->_error_suffix = $suffix;
-
 		return $this;
 	}
 
@@ -304,7 +297,7 @@
 			// Is there a validation rule for the particular URI being accessed?
 			$uri = ($group == '') ? trim($this->CI->uri->ruri_string(), '/') : $group;
 
-			if ($uri != '' AND isset($this->_config_rules[$uri]))
+			if ($uri != '' && isset($this->_config_rules[$uri]))
 			{
 				$this->set_rules($this->_config_rules[$uri]);
 			}
@@ -313,10 +306,10 @@
 				$this->set_rules($this->_config_rules);
 			}
 
-			// We're we able to set the rules correctly?
+			// Were we able to set the rules correctly?
 			if (count($this->_field_data) === 0)
 			{
-				log_message('debug', "Unable to find validation rules");
+				log_message('debug', 'Unable to find validation rules');
 				return FALSE;
 			}
 		}
@@ -330,17 +323,13 @@
 		{
 			// Fetch the data from the corresponding $_POST array and cache it in the _field_data array.
 			// Depending on whether the field name is an array or a string will determine where we get it from.
-
 			if ($row['is_array'] === TRUE)
 			{
 				$this->_field_data[$field]['postdata'] = $this->_reduce_array($_POST, $row['keys']);
 			}
-			else
+			elseif (isset($_POST[$field]) && $_POST[$field] != '')
 			{
-				if (isset($_POST[$field]) AND $_POST[$field] != "")
-				{
-					$this->_field_data[$field]['postdata'] = $_POST[$field];
-				}
+				$this->_field_data[$field]['postdata'] = $_POST[$field];
 			}
 
 			$this->_execute($row, explode('|', $row['rules']), $this->_field_data[$field]['postdata']);
@@ -348,7 +337,6 @@
 
 		// Did we end up with any errors?
 		$total_errors = count($this->_error_array);
-
 		if ($total_errors > 0)
 		{
 			$this->_safe_form_data = TRUE;
@@ -385,7 +373,7 @@
 	/**
 	 * Re-populate the _POST array with our finalized and processed data
 	 *
-	 * @return	null
+	 * @return	void
 	 */
 	protected function _reset_post_array()
 	{
@@ -462,14 +450,12 @@
 			return;
 		}
 
-		// --------------------------------------------------------------------
-
 		// If the field is blank, but NOT required, no further tests are necessary
 		$callback = FALSE;
-		if ( ! in_array('required', $rules) AND is_null($postdata))
+		if ( ! in_array('required', $rules) && is_null($postdata))
 		{
 			// Before we bail out, does the rule contain a callback?
-			if (preg_match("/(callback_\w+(\[.*?\])?)/", implode(' ', $rules), $match))
+			if (preg_match('/(callback_\w+(\[.*?\])?)/', implode(' ', $rules), $match))
 			{
 				$callback = TRUE;
 				$rules = (array('1' => $match[1]));
@@ -480,10 +466,8 @@
 			}
 		}
 
-		// --------------------------------------------------------------------
-
 		// Isset Test. Typically this rule will only apply to checkboxes.
-		if (is_null($postdata) AND $callback === FALSE)
+		if (is_null($postdata) && $callback === FALSE)
 		{
 			if (in_array('isset', $rules, TRUE) OR in_array('required', $rules))
 			{
@@ -526,7 +510,7 @@
 
 			// We set the $postdata variable with the current data in our master array so that
 			// each cycle of the loop is dealing with the processed data from the last cycle
-			if ($row['is_array'] == TRUE AND is_array($this->_field_data[$row['field']]['postdata']))
+			if ($row['is_array'] == TRUE && is_array($this->_field_data[$row['field']]['postdata']))
 			{
 				// We shouldn't need this safety, but just in case there isn't an array index
 				// associated with this cycle we'll bail out
@@ -543,11 +527,9 @@
 				$postdata = $this->_field_data[$row['field']]['postdata'];
 			}
 
-			// --------------------------------------------------------------------
-
 			// Is the rule a callback?
 			$callback = FALSE;
-			if (substr($rule, 0, 9) == 'callback_')
+			if (strpos($rule, 'callback_') === 0)
 			{
 				$rule = substr($rule, 9);
 				$callback = TRUE;
@@ -556,7 +538,7 @@
 			// Strip the parameter (if exists) from the rule
 			// Rules can contain a parameter: max_length[5]
 			$param = FALSE;
-			if (preg_match("/(.*?)\[(.*)\]/", $rule, $match))
+			if (preg_match('/(.*?)\[(.*)\]/', $rule, $match))
 			{
 				$rule	= $match[1];
 				$param	= $match[2];
@@ -567,11 +549,14 @@
 			{
 				if ( ! method_exists($this->CI, $rule))
 				{
-					continue;
+					log_message('debug', 'Unable to find callback validation rule: '.$rule);
+					$result = FALSE;
 				}
-
-				// Run the function and grab the result
-				$result = $this->CI->$rule($postdata, $param);
+				else
+				{
+					// Run the function and grab the result
+					$result = $this->CI->$rule($postdata, $param);
+				}
 
 				// Re-assign the result to the master data array
 				if ($_in_array === TRUE)
@@ -584,7 +569,7 @@
 				}
 
 				// If the field isn't required and we just processed a callback we'll move on...
-				if ( ! in_array('required', $rules, TRUE) AND $result !== FALSE)
+				if ( ! in_array('required', $rules, TRUE) && $result !== FALSE)
 				{
 					continue;
 				}
@@ -597,7 +582,7 @@
 					// Users can use any native PHP function call that has one param.
 					if (function_exists($rule))
 					{
-						$result = $rule($postdata);
+						$result = ($param !== FALSE) ? $rule($postdata, $param) : $rule($postdata);
 
 						if ($_in_array === TRUE)
 						{
@@ -610,13 +595,14 @@
 					}
 					else
 					{
-						log_message('debug', "Unable to find validation rule: ".$rule);
+						log_message('debug', 'Unable to find validation rule: '.$rule);
+						$result = FALSE;
 					}
-
-					continue;
 				}
-
-				$result = $this->$rule($postdata, $param);
+				else
+				{
+					$result = $this->$rule($postdata, $param);
+				}
 
 				if ($_in_array === TRUE)
 				{
@@ -628,7 +614,7 @@
 				}
 			}
 
-			// Did the rule test negatively?  If so, grab the error.
+			// Did the rule test negatively? If so, grab the error.
 			if ($result === FALSE)
 			{
 				if ( ! isset($this->_error_messages[$rule]))
@@ -644,7 +630,7 @@
 				}
 
 				// Is the parameter we are inserting into the error message the name
-				// of another field?  If so we need to grab its "field label"
+				// of another field? If so we need to grab its "field label"
 				if (isset($this->_field_data[$param], $this->_field_data[$param]['label']))
 				{
 					$param = $this->_translate_fieldname($this->_field_data[$param]['label']);
@@ -678,7 +664,7 @@
 	{
 		// Do we need to translate the field name?
 		// We look for the prefix lang: to determine this
-		if (substr($fieldname, 0, 5) === 'lang:')
+		if (strpos($fieldname, 'lang:') === 0)
 		{
 			// Grab the variable
 			$line = substr($fieldname, 5);
@@ -738,15 +724,10 @@
 	{
 		if ( ! isset($this->_field_data[$field]) OR ! isset($this->_field_data[$field]['postdata']))
 		{
-			if ($default === TRUE AND count($this->_field_data) === 0)
-			{
-				return ' selected="selected"';
-			}
-			return '';
+			return ($default === TRUE && count($this->_field_data) === 0) ? ' selected="selected"' : '';
 		}
 
 		$field = $this->_field_data[$field]['postdata'];
-
 		if (is_array($field))
 		{
 			if ( ! in_array($value, $field))
@@ -754,12 +735,9 @@
 				return '';
 			}
 		}
-		else
+		elseif (($field == '' OR $value == '') OR ($field != $value))
 		{
-			if (($field == '' OR $value == '') OR ($field != $value))
-			{
-				return '';
-			}
+			return '';
 		}
 
 		return ' selected="selected"';
@@ -781,15 +759,10 @@
 	{
 		if ( ! isset($this->_field_data[$field]) OR ! isset($this->_field_data[$field]['postdata']))
 		{
-			if ($default === TRUE AND count($this->_field_data) === 0)
-			{
-				return ' checked="checked"';
-			}
-			return '';
+			return ($default === TRUE && count($this->_field_data) === 0) ? ' checked="checked"' : '';
 		}
 
 		$field = $this->_field_data[$field]['postdata'];
-
 		if (is_array($field))
 		{
 			if ( ! in_array($value, $field))
@@ -797,12 +770,9 @@
 				return '';
 			}
 		}
-		else
+		elseif (($field == '' OR $value == '') OR ($field != $value))
 		{
-			if (($field == '' OR $value == '') OR ($field != $value))
-			{
-				return '';
-			}
+			return '';
 		}
 
 		return ' checked="checked"';
@@ -869,9 +839,7 @@
 			return FALSE;
 		}
 
-		$field = $_POST[$field];
-
-		return ($str === $field);
+		return ($str === $_POST[$field]);
 	}
 
 	// --------------------------------------------------------------------
@@ -908,7 +876,7 @@
 	 */
 	public function min_length($str, $val)
 	{
-		if (preg_match("/[^0-9]/", $val))
+		if (preg_match('/[^0-9]/', $val))
 		{
 			return FALSE;
 		}
@@ -932,7 +900,7 @@
 	 */
 	public function max_length($str, $val)
 	{
-		if (preg_match("/[^0-9]/", $val))
+		if (preg_match('/[^0-9]/', $val))
 		{
 			return FALSE;
 		}
@@ -956,7 +924,7 @@
 	 */
 	public function exact_length($str, $val)
 	{
-		if (preg_match("/[^0-9]/", $val))
+		if (preg_match('/[^0-9]/', $val))
 		{
 			return FALSE;
 		}
@@ -1077,19 +1045,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Is Numeric
-	 *
-	 * @param	string
-	 * @return	bool
-	 */
-	public function is_numeric($str)
-	{
-		return is_numeric($str);
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Integer
 	 *
 	 * @param	string
@@ -1170,7 +1125,7 @@
 	 */
 	public function is_natural_no_zero($str)
 	{
-		return ($str != 0 AND preg_match('/^[0-9]+$/', $str));
+		return ($str != 0 && preg_match('/^[0-9]+$/', $str));
 	}
 
 	// --------------------------------------------------------------------
@@ -1217,7 +1172,7 @@
 			return $data;
 		}
 
-		return str_replace(array("'", '"', '<', '>'), array("&#39;", "&quot;", '&lt;', '&gt;'), stripslashes($data));
+		return str_replace(array("'", '"', '<', '>'), array('&#39;', '&quot;', '&lt;', '&gt;'), stripslashes($data));
 	}
 
 	// --------------------------------------------------------------------
@@ -1230,14 +1185,14 @@
 	 */
 	public function prep_url($str = '')
 	{
-		if ($str == 'http://' OR $str == '')
+		if ($str === 'http://' OR $str == '')
 		{
 			return '';
 		}
 
-		if (substr($str, 0, 7) !== 'http://' && substr($str, 0, 8) !== 'https://')
+		if (strpos($str, 'http://') !== 0 && strpos($str, 'https://') !== 0)
 		{
-			$str = 'http://'.$str;
+			return 'http://'.$str;
 		}
 
 		return $str;
@@ -1283,7 +1238,6 @@
 	}
 
 }
-// END Form Validation Class
 
 /* End of file Form_validation.php */
 /* Location: ./system/libraries/Form_validation.php */
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index 10f5507..04ce202 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -54,13 +54,13 @@
 
    -  Added max_filename_increment config setting for Upload library.
    -  CI_Loader::_ci_autoloader() is now a protected method.
-   -  Modified valid_ip() to use PHP's filter_var() when possible (>= PHP 5.2) in the :doc:`Form Validation library <libraries/form_validation>`.
-	 -  Added custom filename to Email::attach() as $this->email->attach($filename, $disposition, $newname)
+   -  Modified valid_ip() to use PHP's filter_var() when possible (>= PHP 5.2) in the :doc:`Input library <libraries/input>` (also used by :doc:`Form Validation library <libraries/form_validation>`).
+   -  Added custom filename to Email::attach() as $this->email->attach($filename, $disposition, $newname)
    -  Cart library changes include:
 	 -  It now auto-increments quantity's instead of just resetting it, this is the default behaviour of large e-commerce sites.
 	 -  Product Name strictness can be disabled via the Cart Library by switching "$product_name_safe"
 	 -  Added function remove() to remove a cart item, updating with quantity of 0 seemed like a hack but has remained to retain compatability
-   -  Image manipulation library changes include:
+   -  :doc:`Image Manipulation library <libraries/image_lib>` changes include:
 	 -  The initialize() method now only sets existing class properties.
 	 -  Added support for 3-length hex color values for wm_font_color and wm_shadow_color properties, as well as validation for them.
 	 -  Class properties wm_font_color, wm_shadow_color and wm_use_drop_shadow are now protected, to avoid breaking the text_watermark() method
@@ -68,6 +68,10 @@
    -  Minor speed optimizations and method & property visibility declarations in the Calendar Library.
    -  Removed SHA1 function in the :doc:`Encryption Library <libraries/encryption>`.
    -  Added $config['csrf_regeneration'] to the CSRF protection in the :doc:`Security library <libraries/security>`, which makes token regeneration optional.
+   -  :doc:`Form Validation library <libraries/form_validation>` changes include:
+	 -  _execute() now considers input data to be invalid if a specified rule is not found.
+	 -  Removed method is_numeric() as it exists as a native PHP function and _execute() will find and use that (the 'is_numeric' rule itself is deprecated since 1.6.1).
+	 -  Native PHP functions used as rules can now accept an additional parameter, other than the data itself.
 
 -  Core
 
@@ -100,11 +104,12 @@
 -  Fixed a bug (#561) - Errors in :doc:`XML-RPC Library <libraries/xmlrpc>` were not properly escaped.
 -  Fixed a bug (#904) - ``CI_Loader::initialize()`` caused a PHP Fatal error to be triggered if error level E_STRICT is used.
 -  Fixed a hosting edge case where an empty $_SERVER['HTTPS'] variable would evaluate to 'on'
+-  Fixed a bug (#11, #183, #863) - CI_Form_validation::_execute() silently continued to the next rule, if a rule method/function is not found.
 
 Version 2.1.0
 =============
 
-Release Date: Not Released
+Release Date: November 14, 2011
 
 -  General Changes
 
diff --git a/user_guide_src/source/libraries/form_validation.rst b/user_guide_src/source/libraries/form_validation.rst
index e7875bc..999ab36 100644
--- a/user_guide_src/source/libraries/form_validation.rst
+++ b/user_guide_src/source/libraries/form_validation.rst
@@ -321,7 +321,7 @@
 function, which removes malicious data.
 
 **Any native PHP function that accepts one parameter can be used as a
-rule, like htmlspecialchars, trim, MD5, etc.**
+rule, like htmlspecialchars, trim, md5, etc.**
 
 .. note:: You will generally want to use the prepping functions
 	**after** the validation rules so if there is an error, the original
@@ -857,8 +857,9 @@
 
 		$this->form_validation->required($string);
 
-.. note:: You can also use any native PHP functions that permit one
-	parameter.
+.. note:: You can also use any native PHP functions that permit up
+	to two parameters, where at least one is required (to pass
+	the field data).
 
 ******************
 Prepping Reference