diff --git a/resources/sql/autopatches/20170301.subtype.01.col.sql b/resources/sql/autopatches/20170301.subtype.01.col.sql
new file mode 100644
--- /dev/null
+++ b/resources/sql/autopatches/20170301.subtype.01.col.sql
@@ -0,0 +1,2 @@
+ALTER TABLE {$NAMESPACE}_search.search_editengineconfiguration
+  ADD subtype VARCHAR(64) COLLATE {$COLLATE_TEXT} NOT NULL;
diff --git a/resources/sql/autopatches/20170301.subtype.02.default.sql b/resources/sql/autopatches/20170301.subtype.02.default.sql
new file mode 100644
--- /dev/null
+++ b/resources/sql/autopatches/20170301.subtype.02.default.sql
@@ -0,0 +1,2 @@
+UPDATE {$NAMESPACE}_search.search_editengineconfiguration
+  SET subtype = 'default' WHERE subtype = '';
diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -2624,6 +2624,8 @@
     'PhabricatorEditEngineSelectCommentAction' => 'applications/transactions/commentaction/PhabricatorEditEngineSelectCommentAction.php',
     'PhabricatorEditEngineSettingsPanel' => 'applications/settings/panel/PhabricatorEditEngineSettingsPanel.php',
     'PhabricatorEditEngineStaticCommentAction' => 'applications/transactions/commentaction/PhabricatorEditEngineStaticCommentAction.php',
+    'PhabricatorEditEngineSubtype' => 'applications/transactions/editengine/PhabricatorEditEngineSubtype.php',
+    'PhabricatorEditEngineSubtypeTestCase' => 'applications/transactions/editengine/__tests__/PhabricatorEditEngineSubtypeTestCase.php',
     'PhabricatorEditEngineTokenizerCommentAction' => 'applications/transactions/commentaction/PhabricatorEditEngineTokenizerCommentAction.php',
     'PhabricatorEditField' => 'applications/transactions/editfield/PhabricatorEditField.php',
     'PhabricatorEditPage' => 'applications/transactions/editengine/PhabricatorEditPage.php',
@@ -7678,6 +7680,8 @@
     'PhabricatorEditEngineSelectCommentAction' => 'PhabricatorEditEngineCommentAction',
     'PhabricatorEditEngineSettingsPanel' => 'PhabricatorSettingsPanel',
     'PhabricatorEditEngineStaticCommentAction' => 'PhabricatorEditEngineCommentAction',
+    'PhabricatorEditEngineSubtype' => 'Phobject',
+    'PhabricatorEditEngineSubtypeTestCase' => 'PhabricatorTestCase',
     'PhabricatorEditEngineTokenizerCommentAction' => 'PhabricatorEditEngineCommentAction',
     'PhabricatorEditField' => 'Phobject',
     'PhabricatorEditPage' => 'Phobject',
diff --git a/src/applications/transactions/editengine/PhabricatorEditEngine.php b/src/applications/transactions/editengine/PhabricatorEditEngine.php
--- a/src/applications/transactions/editengine/PhabricatorEditEngine.php
+++ b/src/applications/transactions/editengine/PhabricatorEditEngine.php
@@ -18,6 +18,8 @@
 
   const EDITENGINECONFIG_DEFAULT = 'default';
 
+  const SUBTYPE_DEFAULT = 'default';
+
   private $viewer;
   private $controller;
   private $isCreate;
diff --git a/src/applications/transactions/editengine/PhabricatorEditEngineSubtype.php b/src/applications/transactions/editengine/PhabricatorEditEngineSubtype.php
new file mode 100644
--- /dev/null
+++ b/src/applications/transactions/editengine/PhabricatorEditEngineSubtype.php
@@ -0,0 +1,36 @@
+<?php
+
+
+final class PhabricatorEditEngineSubtype
+  extends Phobject {
+
+  const SUBTYPE_DEFAULT = 'default';
+
+  public static function validateSubtypeKey($subtype) {
+    if (strlen($subtype) > 64) {
+      throw new Exception(
+        pht(
+          'Subtype "%s" is not valid: subtype keys must be no longer than '.
+          '64 bytes.',
+          $subtype));
+    }
+
+    if (strlen($subtype) < 3) {
+      throw new Exception(
+        pht(
+          'Subtype "%s" is not valid: subtype keys must have a minimum '.
+          'length of 3 bytes.',
+          $subtype));
+    }
+
+    if (!preg_match('/^[a-z]+\z/', $subtype)) {
+      throw new Exception(
+        pht(
+          'Subtype "%s" is not valid: subtype keys may only contain '.
+          'lowercase latin letters ("a" through "z").',
+          $subtype));
+    }
+  }
+
+
+}
diff --git a/src/applications/transactions/editengine/__tests__/PhabricatorEditEngineSubtypeTestCase.php b/src/applications/transactions/editengine/__tests__/PhabricatorEditEngineSubtypeTestCase.php
new file mode 100644
--- /dev/null
+++ b/src/applications/transactions/editengine/__tests__/PhabricatorEditEngineSubtypeTestCase.php
@@ -0,0 +1,38 @@
+<?php
+
+final class PhabricatorEditEngineSubtypeTestCase
+  extends PhabricatorTestCase {
+
+  public function testEditEngineSubtypeKeys() {
+    $map = array(
+      // Too short.
+      'a' => false,
+      'ab' => false,
+
+      // Too long.
+      'mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm'.
+      'mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm' => false,
+
+      // Junk.
+      '!_(#(31 1~' => false,
+
+      // These are reasonable and valid.
+      'default' => true,
+      'bug' => true,
+      'feature' => true,
+      'risk' => true,
+      'security' => true,
+    );
+
+    foreach ($map as $input => $expect) {
+      try {
+        PhabricatorEditEngineSubtype::validateSubtypeKey($input);
+        $actual = true;
+      } catch (Exception $ex) {
+        $actual = false;
+      }
+
+      $this->assertEqual($expect, $actual, pht('Subtype Key "%s"', $input));
+    }
+  }
+}
diff --git a/src/applications/transactions/storage/PhabricatorEditEngineConfiguration.php b/src/applications/transactions/storage/PhabricatorEditEngineConfiguration.php
--- a/src/applications/transactions/storage/PhabricatorEditEngineConfiguration.php
+++ b/src/applications/transactions/storage/PhabricatorEditEngineConfiguration.php
@@ -16,6 +16,7 @@
   protected $isEdit = 0;
   protected $createOrder = 0;
   protected $editOrder = 0;
+  protected $subtype;
 
   private $engine = self::ATTACHABLE;
 
@@ -32,6 +33,7 @@
     PhabricatorEditEngine $engine) {
 
     return id(new PhabricatorEditEngineConfiguration())
+      ->setSubtype(PhabricatorEditEngine::SUBTYPE_DEFAULT)
       ->setEngineKey($engine->getEngineKey())
       ->attachEngine($engine)
       ->setViewPolicy(PhabricatorPolicies::getMostOpenPolicy());
@@ -84,6 +86,7 @@
         'isEdit' => 'bool',
         'createOrder' => 'uint32',
         'editOrder' => 'uint32',
+        'subtype' => 'text64',
       ),
       self::CONFIG_KEY_SCHEMA => array(
         'key_engine' => array(