diff --git a/library/HTMLPurifier/AttrDef/ID.php b/library/HTMLPurifier/AttrDef/ID.php
new file mode 100644
index 00000000..a88386ba
--- /dev/null
+++ b/library/HTMLPurifier/AttrDef/ID.php
@@ -0,0 +1,37 @@
+<?php
+
+require_once 'HTMLPurifier/AttrDef.php';
+require_once 'HTMLPurifier/IDAccumulator.php';
+
+class HTMLPurifier_AttrDef_ID extends HTMLPurifier_AttrDef
+{
+    
+    function validate($id, $accumulator) {
+        
+        $id = @ (string) $id; // sanity check
+        
+        if ($id === '') return false;
+        if (isset($accumulator->ids[$id])) return false;
+        
+        // we purposely avoid using regex, hopefully this is faster
+        
+        if (ctype_alpha($id)) {
+            $result = true;
+        } else {
+            if (!ctype_alpha(@$id[0])) return false;
+            $trim = trim(
+                $id,
+                'A..Za..z0..9:-._'
+              );
+            $result = ($trim === '');
+        }
+        
+        if ($result) $accumulator->add($id);
+        
+        return $result;
+        
+    }
+    
+}
+
+?>
\ No newline at end of file
diff --git a/library/HTMLPurifier/IDAccumulator.php b/library/HTMLPurifier/IDAccumulator.php
index eb6f512f..eb202ab7 100644
--- a/library/HTMLPurifier/IDAccumulator.php
+++ b/library/HTMLPurifier/IDAccumulator.php
@@ -10,6 +10,12 @@ class HTMLPurifier_IDAccumulator
         return $this->ids[$id] = true;
     }
     
+    function load($array_of_ids) {
+        foreach ($array_of_ids as $id) {
+            $this->ids[$id] = true;
+        }
+    }
+    
 }
 
 ?>
\ No newline at end of file
diff --git a/tests/HTMLPurifier/AttrDef/IDTest.php b/tests/HTMLPurifier/AttrDef/IDTest.php
new file mode 100644
index 00000000..0b7d8f5b
--- /dev/null
+++ b/tests/HTMLPurifier/AttrDef/IDTest.php
@@ -0,0 +1,33 @@
+<?php
+
+require_once 'HTMLPurifier/AttrDef/ID.php';
+require_once 'HTMLPurifier/IDAccumulator.php';
+
+class HTMLPurifier_AttrDef_IDTest extends UnitTestCase
+{
+    
+    function test() {
+        
+        $acc = new HTMLPurifier_IDAccumulator();
+        
+        $def = new HTMLPurifier_AttrDef_ID();
+        
+        // valid ID names
+        $this->assertTrue($def->validate('alpha', $acc));
+        $this->assertTrue($def->validate('al_ha', $acc));
+        $this->assertTrue($def->validate('a0-:.', $acc));
+        $this->assertTrue($def->validate('a'    , $acc));
+        
+        // invalid ID names
+        $this->assertFalse($def->validate('<asa', $acc));
+        $this->assertFalse($def->validate('0123', $acc));
+        $this->assertFalse($def->validate('.asa', $acc));
+        
+        // test duplicate detection
+        $this->assertFalse($def->validate('a'   , $acc));
+        
+    }
+    
+}
+
+?>
\ No newline at end of file
diff --git a/tests/HTMLPurifier/IDAccumulatorTest.php b/tests/HTMLPurifier/IDAccumulatorTest.php
index b5a82d3c..8ff04545 100644
--- a/tests/HTMLPurifier/IDAccumulatorTest.php
+++ b/tests/HTMLPurifier/IDAccumulatorTest.php
@@ -14,6 +14,20 @@ class HTMLPurifier_IDAccumulatorTest extends UnitTestCase
         $this->assertTrue( $accumulator->add('id2'));
         $this->assertFalse($accumulator->add('id1')); // repeated id
         
+        // you can also access the properties (they're public)
+        $this->assertTrue( isset($accumulator->ids['id2']) );
+        
+    }
+    
+    function testLoad() {
+        
+        $accumulator = new HTMLPurifier_IDAccumulator();
+        
+        $accumulator->load(array('id1', 'id2', 'id3'));
+        
+        $this->assertFalse($accumulator->add('id1')); // repeated id
+        $this->assertTrue($accumulator->add('id4'));
+        
     }
     
 }
diff --git a/tests/index.php b/tests/index.php
index 05ec1b4a..d87e2d0d 100644
--- a/tests/index.php
+++ b/tests/index.php
@@ -33,6 +33,7 @@ $test->addTestFile('HTMLPurifier/Strategy/FixNestingTest.php');
 $test->addTestFile('HTMLPurifier/Strategy/CompositeTest.php');
 $test->addTestFile('HTMLPurifier/Strategy/CoreTest.php');
 $test->addTestFile('HTMLPurifier/AttrDef/EnumTest.php');
+$test->addTestFile('HTMLPurifier/AttrDef/IDTest.php');
 $test->addTestFile('HTMLPurifier/IDAccumulatorTest.php');
 
 $test->run( new HtmlReporter() );