diff --git a/library/Zend/Pdf/Element.php b/library/Zend/Pdf/Element.php
index 1a92dea..7ec0c91 100644
--- a/library/Zend/Pdf/Element.php
+++ b/library/Zend/Pdf/Element.php
@@ -45,13 +45,6 @@ abstract class Zend_Pdf_Element
      */
     private $_parentObject = null;
 
-    /**
-     * Object value
-     *
-     * @var string
-     */
-    public $value;
-
     /**
      * Return type of the element.
      * See ZPdfPDFConst for possible values
@@ -138,10 +131,7 @@ public function cleanUp()
      *
      * @return mixed
      */
-    public function toPhp()
-    {
-        return $this->value;
-    }
+    abstract public function toPhp();
 
     /**
      * Convert PHP value into PDF element.
diff --git a/library/Zend/Pdf/Element/Boolean.php b/library/Zend/Pdf/Element/Boolean.php
index b0edd67..4cf5e90 100644
--- a/library/Zend/Pdf/Element/Boolean.php
+++ b/library/Zend/Pdf/Element/Boolean.php
@@ -34,6 +34,14 @@
  */
 class Zend_Pdf_Element_Boolean extends Zend_Pdf_Element
 {
+    /**
+     * Object value
+     *
+     * @var boolean
+     */
+    public $value;
+
+
     /**
      * Object constructor
      *
@@ -72,4 +80,15 @@ public function toString($factory = null)
     {
         return $this->value ? 'true' : 'false';
     }
+
+
+    /**
+     * Convert PDF element to PHP type.
+     *
+     * @return boolean
+     */
+    public function toPhp()
+    {
+        return $this->value;
+    }
 }
diff --git a/library/Zend/Pdf/Element/Name.php b/library/Zend/Pdf/Element/Name.php
index de08f39..89c3daf 100644
--- a/library/Zend/Pdf/Element/Name.php
+++ b/library/Zend/Pdf/Element/Name.php
@@ -34,6 +34,14 @@
  */
 class Zend_Pdf_Element_Name extends Zend_Pdf_Element
 {
+    /**
+     * Object value
+     *
+     * @var string
+     */
+    public $value;
+
+
     /**
      * Object constructor
      *
@@ -150,4 +158,15 @@ public function toString($factory = null)
     {
         return '/' . self::escape((string)$this->value);
     }
+
+
+    /**
+     * Convert PDF element to PHP type.
+     *
+     * @return string
+     */
+    public function toPhp()
+    {
+        return $this->value;
+    }
 }
diff --git a/library/Zend/Pdf/Element/Null.php b/library/Zend/Pdf/Element/Null.php
index d2b435a..9089e92 100644
--- a/library/Zend/Pdf/Element/Null.php
+++ b/library/Zend/Pdf/Element/Null.php
@@ -34,6 +34,14 @@
  */
 class Zend_Pdf_Element_Null extends Zend_Pdf_Element
 {
+    /**
+     * Object value. Always null.
+     *
+     * @var mixed
+     */
+    public $value;
+
+
     /**
      * Object constructor
      */
@@ -64,4 +72,15 @@ public function toString($factory = null)
     {
         return 'null';
     }
+
+
+    /**
+     * Convert PDF element to PHP type.
+     *
+     * @return mixed
+     */
+    public function toPhp()
+    {
+        return $this->value;
+    }
 }
diff --git a/library/Zend/Pdf/Element/Numeric.php b/library/Zend/Pdf/Element/Numeric.php
index e039421..f8f0672 100644
--- a/library/Zend/Pdf/Element/Numeric.php
+++ b/library/Zend/Pdf/Element/Numeric.php
@@ -34,6 +34,14 @@
  */
 class Zend_Pdf_Element_Numeric extends Zend_Pdf_Element
 {
+    /**
+     * Object value
+     *
+     * @var numeric
+     */
+    public $value;
+
+
     /**
      * Object constructor
      *
@@ -84,4 +92,15 @@ public function toString($factory = null)
         }
         return sprintf("%.{$prec}F", $this->value);
     }
+
+
+    /**
+     * Convert PDF element to PHP type.
+     *
+     * @return numeric
+     */
+    public function toPhp()
+    {
+        return $this->value;
+    }
 }
diff --git a/library/Zend/Pdf/Element/Stream.php b/library/Zend/Pdf/Element/Stream.php
index 37b88dc..7148da1 100644
--- a/library/Zend/Pdf/Element/Stream.php
+++ b/library/Zend/Pdf/Element/Stream.php
@@ -37,6 +37,14 @@
  */
 class Zend_Pdf_Element_Stream extends Zend_Pdf_Element
 {
+    /**
+     * Object value
+     *
+     * @var Zend_Memory_Container
+     */
+    public $value;
+
+
     /**
      * Object constructor
      *
@@ -119,4 +127,14 @@ public function toString($factory = null)
     {
         return "stream\n" . $this->value->getRef() . "\nendstream";
     }
+
+    /**
+     * Convert PDF element to PHP type.
+     *
+     * @return Zend_Memory_Container
+     */
+    public function toPhp()
+    {
+        return $this->value;
+    }
 }
diff --git a/library/Zend/Pdf/Element/String.php b/library/Zend/Pdf/Element/String.php
index 5a1a88c..b9817b3 100644
--- a/library/Zend/Pdf/Element/String.php
+++ b/library/Zend/Pdf/Element/String.php
@@ -33,6 +33,13 @@
  */
 class Zend_Pdf_Element_String extends Zend_Pdf_Element
 {
+    /**
+     * Object value
+     *
+     * @var string
+     */
+    public $value;
+
     /**
      * Object constructor
      *
@@ -67,6 +74,17 @@ public function toString($factory = null)
     }
 
 
+    /**
+     * Convert PDF element to PHP type.
+     *
+     * @return string
+     */
+    public function toPhp()
+    {
+        return $this->value;
+    }
+
+
     /**
      * Escape string according to the PDF rules
      *