diff --git a/Classes/PHPExcel/Calculation.php b/Classes/PHPExcel/Calculation.php
index 2b3099a..9e51ea3 100644
--- a/Classes/PHPExcel/Calculation.php
+++ b/Classes/PHPExcel/Calculation.php
@@ -53,7 +53,7 @@ if (!defined('CALCULATION_REGEXP_CELLREF')) {
 
 
 /**
- * PHPExcel_Calculation (Singleton)
+ * PHPExcel_Calculation (Multiton)
  *
  * @category	PHPExcel
  * @package		PHPExcel_Calculation
@@ -105,7 +105,7 @@ class PHPExcel_Calculation {
     private $_workbook;
 
 	/**
-	 * List of instances of the calculation engine that we've instantiated
+	 * List of instances of the calculation engine that we've instantiated for individual workbooks
 	 *
 	 * @access	private
 	 * @var PHPExcel_Calculation[]
@@ -194,26 +194,80 @@ class PHPExcel_Calculation {
 	 */
 	private $_cyclicReferenceStack;
 
+	/**
+	 * Current iteration counter for cyclic formulae
+	 * If the value is 0 (or less) then cyclic formulae will throw an exception,
+	 *    otherwise they will iterate to the limit defined here before returning a result
+	 *
+	 * @var integer
+	 *
+	 */
 	private $_cyclicFormulaCount = 0;
+
 	private $_cyclicFormulaCell = '';
+
+	/**
+	 * Number of iterations for cyclic formulae
+	 *
+	 * @var integer
+	 *
+	 */
 	public $cyclicFormulaCount = 0;
 
-
+	/**
+	 * Precision used for calculations
+	 *
+	 * @var integer
+	 *
+	 */
 	private $_savedPrecision	= 14;
 
 
+	/**
+	 * The current locale setting
+	 *
+	 * @var string
+	 *
+	 */
 	private static $_localeLanguage = 'en_us';					//	US English	(default locale)
+
+	/**
+	 * List of available locale settings
+	 * Note that this is read for the locale subdirectory only when requested
+	 *
+	 * @var string[]
+	 *
+	 */
 	private static $_validLocaleLanguages = array(	'en'		//	English		(default language)
 												 );
+	/**
+	 * Locale-specific argument separator for function arguments
+	 *
+	 * @var string
+	 *
+	 */
 	private static $_localeArgumentSeparator = ',';
 	private static $_localeFunctions = array();
+
+	/**
+	 * Locale-specific translations for Excel constants (True, False and Null)
+	 *
+	 * @var string[]
+	 *
+	 */
 	public static $_localeBoolean = array(	'TRUE'	=> 'TRUE',
 											'FALSE'	=> 'FALSE',
 											'NULL'	=> 'NULL'
 										  );
 
 
-	//	Constant conversion from text name/value to actual (datatyped) value
+	/**
+	 * Excel constant string translations to their PHP equivalents
+	 * Constant conversion from text name/value to actual (datatyped) value
+	 *
+	 * @var string[]
+	 *
+	 */
 	private static $_ExcelConstants = array('TRUE'	=> TRUE,
 											'FALSE'	=> FALSE,
 											'NULL'	=> NULL
diff --git a/Classes/PHPExcel/Chart.php b/Classes/PHPExcel/Chart.php
index 3e9572d..4c6d5e3 100644
--- a/Classes/PHPExcel/Chart.php
+++ b/Classes/PHPExcel/Chart.php
@@ -378,6 +378,13 @@ class PHPExcel_Chart
 		return $this;
 	}
 
+	/**
+	 * Set the offset position within the Top Left cell for the chart
+	 *
+	 * @param	integer	$xOffset
+	 * @param	integer	$yOffset
+	 * @return PHPExcel_Chart
+	 */
 	public function setTopLeftOffset($xOffset=null,$yOffset=null) {
 		if (!is_null($xOffset))
 			$this->setTopLeftXOffset($xOffset);
@@ -387,6 +394,11 @@ class PHPExcel_Chart
 		return $this;
 	}
 
+	/**
+	 * Get the offset position within the Top Left cell for the chart
+	 *
+	 * @return integer[]
+	 */
 	public function getTopLeftOffset() {
 		return array( 'X' => $this->_topLeftXOffset,
 					  'Y' => $this->_topLeftYOffset
@@ -458,6 +470,13 @@ class PHPExcel_Chart
 		return $this->_bottomRightCellRef;
 	}
 
+	/**
+	 * Set the offset position within the Bottom Right cell for the chart
+	 *
+	 * @param	integer	$xOffset
+	 * @param	integer	$yOffset
+	 * @return PHPExcel_Chart
+	 */
 	public function setBottomRightOffset($xOffset=null,$yOffset=null) {
 		if (!is_null($xOffset))
 			$this->setBottomRightXOffset($xOffset);
@@ -467,6 +486,11 @@ class PHPExcel_Chart
 		return $this;
 	}
 
+	/**
+	 * Get the offset position within the Bottom Right cell for the chart
+	 *
+	 * @return integer[]
+	 */
 	public function getBottomRightOffset() {
 		return array( 'X' => $this->_bottomRightXOffset,
 					  'Y' => $this->_bottomRightYOffset