Index: src/__phutil_library_map__.php
===================================================================
--- src/__phutil_library_map__.php
+++ src/__phutil_library_map__.php
@@ -358,6 +358,8 @@
     'DifferentialCustomFieldDependsOnParser' => 'applications/differential/field/parser/DifferentialCustomFieldDependsOnParser.php',
     'DifferentialCustomFieldDependsOnParserTestCase' => 'applications/differential/field/parser/__tests__/DifferentialCustomFieldDependsOnParserTestCase.php',
     'DifferentialCustomFieldNumericIndex' => 'applications/differential/storage/DifferentialCustomFieldNumericIndex.php',
+    'DifferentialCustomFieldRevertsParser' => 'applications/differential/field/parser/DifferentialCustomFieldRevertsParser.php',
+    'DifferentialCustomFieldRevertsParserTestCase' => 'applications/differential/field/parser/__tests__/DifferentialCustomFieldRevertsParserTestCase.php',
     'DifferentialCustomFieldStorage' => 'applications/differential/storage/DifferentialCustomFieldStorage.php',
     'DifferentialCustomFieldStringIndex' => 'applications/differential/storage/DifferentialCustomFieldStringIndex.php',
     'DifferentialDAO' => 'applications/differential/storage/DifferentialDAO.php',
@@ -387,7 +389,6 @@
     'DifferentialFieldSpecificationIncompleteException' => 'applications/differential/field/exception/DifferentialFieldSpecificationIncompleteException.php',
     'DifferentialFieldValidationException' => 'applications/differential/field/exception/DifferentialFieldValidationException.php',
     'DifferentialFreeformFieldSpecification' => 'applications/differential/field/specification/DifferentialFreeformFieldSpecification.php',
-    'DifferentialFreeformFieldTestCase' => 'applications/differential/field/specification/__tests__/DifferentialFreeformFieldTestCase.php',
     'DifferentialGetWorkingCopy' => 'applications/differential/DifferentialGetWorkingCopy.php',
     'DifferentialGitSVNIDFieldSpecification' => 'applications/differential/field/specification/DifferentialGitSVNIDFieldSpecification.php',
     'DifferentialHostFieldSpecification' => 'applications/differential/field/specification/DifferentialHostFieldSpecification.php',
@@ -2876,6 +2877,8 @@
     'DifferentialCustomFieldDependsOnParser' => 'PhabricatorCustomFieldMonogramParser',
     'DifferentialCustomFieldDependsOnParserTestCase' => 'PhabricatorTestCase',
     'DifferentialCustomFieldNumericIndex' => 'PhabricatorCustomFieldNumericIndexStorage',
+    'DifferentialCustomFieldRevertsParser' => 'PhabricatorCustomFieldMonogramParser',
+    'DifferentialCustomFieldRevertsParserTestCase' => 'PhabricatorTestCase',
     'DifferentialCustomFieldStorage' => 'PhabricatorCustomFieldStorage',
     'DifferentialCustomFieldStringIndex' => 'PhabricatorCustomFieldStringIndexStorage',
     'DifferentialDAO' => 'PhabricatorLiskDAO',
@@ -2908,7 +2911,6 @@
     'DifferentialFieldSpecificationIncompleteException' => 'Exception',
     'DifferentialFieldValidationException' => 'Exception',
     'DifferentialFreeformFieldSpecification' => 'DifferentialFieldSpecification',
-    'DifferentialFreeformFieldTestCase' => 'PhabricatorTestCase',
     'DifferentialGitSVNIDFieldSpecification' => 'DifferentialFieldSpecification',
     'DifferentialHostFieldSpecification' => 'DifferentialFieldSpecification',
     'DifferentialHovercardEventListener' => 'PhabricatorEventListener',
Index: src/applications/differential/field/parser/DifferentialCustomFieldDependsOnParser.php
===================================================================
--- src/applications/differential/field/parser/DifferentialCustomFieldDependsOnParser.php
+++ src/applications/differential/field/parser/DifferentialCustomFieldDependsOnParser.php
@@ -26,7 +26,7 @@
   }
 
   protected function getMonogramPattern() {
-    return 'D\d+';
+    return '[Dd]\d+';
   }
 
 }
Index: src/applications/differential/field/parser/DifferentialCustomFieldRevertsParser.php
===================================================================
--- /dev/null
+++ src/applications/differential/field/parser/DifferentialCustomFieldRevertsParser.php
@@ -0,0 +1,51 @@
+<?php
+
+final class DifferentialCustomFieldRevertsParser
+  extends PhabricatorCustomFieldMonogramParser {
+
+  protected function getPrefixes() {
+
+    // NOTE: Git language is "This reverts commit X."
+    // NOTE: Mercurial language is "Backed out changeset Y".
+
+    return array(
+      'revert',
+      'reverts',
+      'reverted',
+      'backout',
+      'backsout',
+      'backedout',
+      'back out',
+      'backs out',
+      'backed out',
+      'undo',
+      'undoes',
+    );
+  }
+
+  protected function getInfixes() {
+    return array(
+      'commit',
+      'commits',
+      'change',
+      'changes',
+      'changeset',
+      'changesets',
+      'rev',
+      'revs',
+      'revision',
+      'revisions',
+      'diff',
+      'diffs',
+    );
+  }
+
+  protected function getSuffixes() {
+    return array();
+  }
+
+  protected function getMonogramPattern() {
+    return '[rA-Z0-9a-f]+';
+  }
+
+}
Index: src/applications/differential/field/parser/__tests__/DifferentialCustomFieldDependsOnParserTestCase.php
===================================================================
--- src/applications/differential/field/parser/__tests__/DifferentialCustomFieldDependsOnParserTestCase.php
+++ src/applications/differential/field/parser/__tests__/DifferentialCustomFieldDependsOnParserTestCase.php
@@ -27,12 +27,12 @@
           'offset' => 0,
         ),
       ),
-      'depends on D123, D124' => array(
+      'depends on D123, d124' => array(
         array(
-          'match' => 'depends on D123, D124',
+          'match' => 'depends on D123, d124',
           'prefix' => 'depends on',
           'infix' => '',
-          'monograms' => array('D123', 'D124'),
+          'monograms' => array('D123', 'd124'),
           'suffix' => '',
           'offset' => 0,
         ),
Index: src/applications/differential/field/parser/__tests__/DifferentialCustomFieldRevertsParserTestCase.php
===================================================================
--- /dev/null
+++ src/applications/differential/field/parser/__tests__/DifferentialCustomFieldRevertsParserTestCase.php
@@ -0,0 +1,92 @@
+<?php
+
+final class DifferentialCustomFieldRevertsParserTestCase
+  extends PhabricatorTestCase {
+
+  public function testParser() {
+    $map = array(
+      'quack quack quack' => array(),
+
+      // Git default message.
+      'This reverts commit 1234abcd.' => array(
+        array(
+          'match' => 'reverts commit 1234abcd',
+          'prefix' => 'reverts',
+          'infix' => 'commit',
+          'monograms' => array('1234abcd'),
+          'suffix' => '',
+          'offset' => 5,
+        ),
+      ),
+
+      // Mercurial default message.
+      'Backed out changeset 1234abcd.' => array(
+        array(
+          'match' => 'Backed out changeset 1234abcd',
+          'prefix' => 'Backed out',
+          'infix' => 'changeset',
+          'monograms' => array('1234abcd'),
+          'suffix' => '',
+          'offset' => 0,
+        ),
+      ),
+
+      'this undoes 1234abcd, 5678efab. they were bad' => array(
+        array(
+          'match' => 'undoes 1234abcd, 5678efab',
+          'prefix' => 'undoes',
+          'infix' => '',
+          'monograms' => array('1234abcd', '5678efab'),
+          'suffix' => '',
+          'offset' => 5,
+        ),
+      ),
+
+      "Reverts 123" => array(
+        array(
+          'match' => 'Reverts 123',
+          'prefix' => 'Reverts',
+          'infix' => '',
+          'monograms' => array('123'),
+          'suffix' => '',
+          'offset' => 0,
+        ),
+      ),
+
+
+      "Reverts r123" => array(
+        array(
+          'match' => 'Reverts r123',
+          'prefix' => 'Reverts',
+          'infix' => '',
+          'monograms' => array('r123'),
+          'suffix' => '',
+          'offset' => 0,
+        ),
+      ),
+
+      "Backs out commit\n99\n100" => array(
+        array(
+          'match' => "Backs out commit\n99\n100",
+          'prefix' => 'Backs out',
+          'infix' => 'commit',
+          'monograms' => array('99', '100'),
+          'suffix' => '',
+          'offset' => 0,
+        ),
+      ),
+
+      "This doesn't revert anything" => array(),
+      'nonrevert of r11' => array(),
+      "fixed a bug" => array(),
+    );
+
+    foreach ($map as $input => $expect) {
+      $parser = new DifferentialCustomFieldRevertsParser();
+      $output = $parser->parseCorpus($input);
+
+      $this->assertEqual($expect, $output, $input);
+    }
+  }
+
+}
Index: src/applications/differential/field/specification/__tests__/DifferentialFreeformFieldTestCase.php
===================================================================
--- src/applications/differential/field/specification/__tests__/DifferentialFreeformFieldTestCase.php
+++ /dev/null
@@ -1,31 +0,0 @@
-<?php
-
-final class DifferentialFreeformFieldTestCase extends PhabricatorTestCase {
-
-  public function testRevertedCommitParser() {
-    $map = array(
-      "Reverts 123" => array('123'),
-      "Reverts r123" => array('r123'),
-      "Reverts ac382f2" => array('ac382f2'),
-      "Reverts r22, r23" => array('r22', 'r23'),
-      "Reverts D99" => array('D99'),
-      "Backs out commit\n99\n100" => array('99', '100'),
-      "undo change f9f9f8f8" => array('f9f9f8f8'),
-      "Backedout Changeset rX1234" => array('rX1234'),
-      "This doesn't revert anything" => array(),
-      'nonrevert of r11' => array(),
-      "fixed a bug" => array(),
-    );
-
-    foreach ($map as $input => $expect) {
-      $actual = array_values(
-        DifferentialFreeformFieldSpecification::findRevertedCommits($input));
-
-      $this->assertEqual(
-        $expect,
-        $actual,
-        "Reverted commits in: {$input}");
-    }
-  }
-
-}
Index: src/infrastructure/customfield/parser/PhabricatorCustomFieldMonogramParser.php
===================================================================
--- src/infrastructure/customfield/parser/PhabricatorCustomFieldMonogramParser.php
+++ src/infrastructure/customfield/parser/PhabricatorCustomFieldMonogramParser.php
@@ -27,7 +27,7 @@
       '((?:'.$monogram_pattern.'[,\s]*)+)'.
       $suffix_regex.
       '(?:$|\b)'.
-      '/i';
+      '/';
 
     $matches = null;
     $ok = preg_match_all(
@@ -65,7 +65,7 @@
     $maybe_tail = $final ? '' : '\s+';
     $maybe_optional = $optional ? '?' : '';
 
-    return '(?:('.$parts.')'.$maybe_tail.')'.$maybe_optional;
+    return '(?i:('.$parts.')'.$maybe_tail.')'.$maybe_optional;
   }
 
 }