diff --git a/src/applications/calendar/xaction/PhabricatorCalendarEventDescriptionTransaction.php b/src/applications/calendar/xaction/PhabricatorCalendarEventDescriptionTransaction.php
index 9c14f1ae80..343ffa2adf 100644
--- a/src/applications/calendar/xaction/PhabricatorCalendarEventDescriptionTransaction.php
+++ b/src/applications/calendar/xaction/PhabricatorCalendarEventDescriptionTransaction.php
@@ -1,42 +1,53 @@
 <?php
 
 final class PhabricatorCalendarEventDescriptionTransaction
   extends PhabricatorCalendarEventTransactionType {
 
   const TRANSACTIONTYPE = 'calendar.description';
 
   public function generateOldValue($object) {
     return $object->getDescription();
   }
 
   public function applyInternalEffects($object, $value) {
     $object->setDescription($value);
   }
 
   public function getTitle() {
     return pht(
       '%s updated the event description.',
       $this->renderAuthor());
   }
 
   public function getTitleForFeed() {
     return pht(
       '%s updated the event description for %s.',
       $this->renderAuthor(),
       $this->renderObject());
   }
 
   public function hasChangeDetailView() {
     return true;
   }
 
   public function newChangeDetailView() {
     $viewer = $this->getViewer();
 
     return id(new PhabricatorApplicationTransactionTextDiffDetailView())
       ->setViewer($viewer)
       ->setOldText($this->getOldValue())
       ->setNewText($this->getNewValue());
   }
 
+  public function newRemarkupChanges() {
+    $changes = array();
+
+    $changes[] = $this->newRemarkupChange()
+      ->setOldValue($this->getOldValue())
+      ->setNewValue($this->getNewValue());
+
+    return $changes;
+  }
+
+
 }
diff --git a/src/applications/transactions/storage/PhabricatorModularTransaction.php b/src/applications/transactions/storage/PhabricatorModularTransaction.php
index 8ea6248563..c93a559108 100644
--- a/src/applications/transactions/storage/PhabricatorModularTransaction.php
+++ b/src/applications/transactions/storage/PhabricatorModularTransaction.php
@@ -1,152 +1,156 @@
 <?php
 
 abstract class PhabricatorModularTransaction
   extends PhabricatorApplicationTransaction {
 
   private $implementation;
 
   abstract public function getBaseTransactionClass();
 
   final protected function getTransactionImplementation() {
     if (!$this->implementation) {
       $this->implementation = $this->newTransactionImplementation();
     }
 
     return $this->implementation;
   }
 
   public function newModularTransactionTypes() {
     $base_class = $this->getBaseTransactionClass();
 
     $types = id(new PhutilClassMapQuery())
       ->setAncestorClass($base_class)
       ->setUniqueMethod('getTransactionTypeConstant')
       ->execute();
 
     // Add core transaction types.
     $types += id(new PhutilClassMapQuery())
       ->setAncestorClass('PhabricatorCoreTransactionType')
       ->setUniqueMethod('getTransactionTypeConstant')
       ->execute();
 
     return $types;
   }
 
   private function newTransactionImplementation() {
     $types = $this->newModularTransactionTypes();
 
     $key = $this->getTransactionType();
 
     if (empty($types[$key])) {
       $type = new PhabricatorCoreVoidTransaction();
     } else {
       $type = clone $types[$key];
     }
 
     $type->setStorage($this);
 
     return $type;
   }
 
   final public function generateOldValue($object) {
     return $this->getTransactionImplementation()->generateOldValue($object);
   }
 
   final public function generateNewValue($object) {
     return $this->getTransactionImplementation()
       ->generateNewValue($object, $this->getNewValue());
   }
 
   final public function willApplyTransactions($object, array $xactions) {
     return $this->getTransactionImplementation()
       ->willApplyTransactions($object, $xactions);
   }
 
   final public function applyInternalEffects($object) {
     return $this->getTransactionImplementation()
       ->applyInternalEffects($object);
   }
 
   final public function applyExternalEffects($object) {
     return $this->getTransactionImplementation()
       ->applyExternalEffects($object);
   }
 
   final public function shouldHide() {
     if ($this->getTransactionImplementation()->shouldHide()) {
       return true;
     }
 
     return parent::shouldHide();
   }
 
   final public function getIcon() {
     $icon = $this->getTransactionImplementation()->getIcon();
     if ($icon !== null) {
       return $icon;
     }
 
     return parent::getIcon();
   }
 
   final public function getTitle() {
     $title = $this->getTransactionImplementation()->getTitle();
     if ($title !== null) {
       return $title;
     }
 
     return parent::getTitle();
   }
 
   public function getTitleForMail() {
     $old_target = $this->getRenderingTarget();
     $new_target = self::TARGET_TEXT;
     $this->setRenderingTarget($new_target);
     $title = $this->getTitle();
     $this->setRenderingTarget($old_target);
     return $title;
   }
 
   final public function getTitleForFeed() {
     $title = $this->getTransactionImplementation()->getTitleForFeed();
     if ($title !== null) {
       return $title;
     }
 
     return parent::getTitleForFeed();
   }
 
   final public function getColor() {
     $color = $this->getTransactionImplementation()->getColor();
     if ($color !== null) {
       return $color;
     }
 
     return parent::getColor();
   }
 
   public function attachViewer(PhabricatorUser $viewer) {
     $this->getTransactionImplementation()->setViewer($viewer);
     return parent::attachViewer($viewer);
   }
 
   final public function hasChangeDetails() {
     if ($this->getTransactionImplementation()->hasChangeDetailView()) {
       return true;
     }
 
     return parent::hasChangeDetails();
   }
 
   final public function renderChangeDetails(PhabricatorUser $viewer) {
     $impl = $this->getTransactionImplementation();
     $impl->setViewer($viewer);
     $view = $impl->newChangeDetailView();
     if ($view !== null) {
       return $view;
     }
 
     return parent::renderChangeDetails($viewer);
   }
 
+  final protected function newRemarkupChanges() {
+    return $this->getTransactionImplementation()->newRemarkupChanges();
+  }
+
 }
diff --git a/src/applications/transactions/storage/PhabricatorModularTransactionType.php b/src/applications/transactions/storage/PhabricatorModularTransactionType.php
index a35eb02cd3..a5ddcc3e94 100644
--- a/src/applications/transactions/storage/PhabricatorModularTransactionType.php
+++ b/src/applications/transactions/storage/PhabricatorModularTransactionType.php
@@ -1,256 +1,265 @@
 <?php
 
 abstract class PhabricatorModularTransactionType
   extends Phobject {
 
   private $storage;
   private $viewer;
   private $editor;
 
   final public function getTransactionTypeConstant() {
     return $this->getPhobjectClassConstant('TRANSACTIONTYPE');
   }
 
   public function generateOldValue($object) {
     throw new PhutilMethodNotImplementedException();
   }
 
   public function generateNewValue($object, $value) {
     return $value;
   }
 
   public function validateTransactions($object, array $xactions) {
     return array();
   }
 
   public function willApplyTransactions($object, array $xactions) {
     return;
   }
 
   public function applyInternalEffects($object, $value) {
     return;
   }
 
   public function applyExternalEffects($object, $value) {
     return;
   }
 
   public function extractFilePHIDs($object, $value) {
     return array();
   }
 
   public function shouldHide() {
     return false;
   }
 
   public function getIcon() {
     return null;
   }
 
   public function getTitle() {
     return null;
   }
 
   public function getTitleForFeed() {
     return null;
   }
 
   public function getColor() {
     return null;
   }
 
   public function hasChangeDetailView() {
     return false;
   }
 
   public function newChangeDetailView() {
     throw new PhutilMethodNotImplementedException();
   }
 
+  public function newRemarkupChanges() {
+    return array();
+  }
+
   final public function setStorage(
     PhabricatorApplicationTransaction $xaction) {
     $this->storage = $xaction;
     return $this;
   }
 
   private function getStorage() {
     return $this->storage;
   }
 
   final public function setViewer(PhabricatorUser $viewer) {
     $this->viewer = $viewer;
     return $this;
   }
 
   final protected function getViewer() {
     return $this->viewer;
   }
 
   final public function getActor() {
     return $this->getEditor()->getActor();
   }
 
   final public function getActingAsPHID() {
     return $this->getEditor()->getActingAsPHID();
   }
 
   final public function setEditor(
     PhabricatorApplicationTransactionEditor $editor) {
     $this->editor = $editor;
     return $this;
   }
 
   final protected function getEditor() {
     if (!$this->editor) {
       throw new PhutilInvalidStateException('setEditor');
     }
     return $this->editor;
   }
 
   final protected function getAuthorPHID() {
     return $this->getStorage()->getAuthorPHID();
   }
 
   final protected function getObjectPHID() {
     return $this->getStorage()->getObjectPHID();
   }
 
   final protected function getObject() {
     return $this->getStorage()->getObject();
   }
 
   final protected function getOldValue() {
     return $this->getStorage()->getOldValue();
   }
 
   final protected function getNewValue() {
     return $this->getStorage()->getNewValue();
   }
 
   final protected function renderAuthor() {
     $author_phid = $this->getAuthorPHID();
     return $this->getStorage()->renderHandleLink($author_phid);
   }
 
   final protected function renderObject() {
     $object_phid = $this->getObjectPHID();
     return $this->getStorage()->renderHandleLink($object_phid);
   }
 
   final protected function renderHandle($phid) {
     $viewer = $this->getViewer();
     $display = $viewer->renderHandle($phid);
 
     if ($this->isTextMode()) {
       $display->setAsText(true);
     }
 
     return $display;
   }
 
   final protected function renderOldHandle() {
     return $this->renderHandle($this->getOldValue());
   }
 
   final protected function renderNewHandle() {
     return $this->renderHandle($this->getNewValue());
   }
 
   final protected function renderHandleList(array $phids) {
     $viewer = $this->getViewer();
     $display = $viewer->renderHandleList($phids)
       ->setAsInline(true);
 
     if ($this->isTextMode()) {
       $display->setAsText(true);
     }
 
     return $display;
   }
 
   final protected function renderValue($value) {
     if ($this->isTextMode()) {
       return sprintf('"%s"', $value);
     }
 
     return phutil_tag(
       'span',
       array(
         'class' => 'phui-timeline-value',
       ),
       $value);
   }
 
   final protected function renderOldValue() {
     return $this->renderValue($this->getOldValue());
   }
 
   final protected function renderNewValue() {
     return $this->renderValue($this->getNewValue());
   }
 
   final protected function renderDate($epoch) {
     $viewer = $this->getViewer();
 
     $display = phabricator_datetime($epoch, $viewer);
 
     // When rendering to text, we explicitly render the offset from UTC to
     // provide context to the date: the mail may be generating with the
     // server's settings, or the user may later refer back to it after changing
     // timezones.
 
     if ($this->isTextMode()) {
       $offset = $viewer->getTimeZoneOffsetInHours();
       if ($offset >= 0) {
         $display = pht('%s (UTC+%d)', $display, $offset);
       } else {
         $display = pht('%s (UTC-%d)', $display, abs($offset));
       }
     }
 
     return $this->renderValue($display);
   }
 
   final protected function renderOldDate() {
     return $this->renderDate($this->getOldValue());
   }
 
   final protected function renderNewDate() {
     return $this->renderDate($this->getNewValue());
   }
 
   final protected function newError($title, $message, $xaction = null) {
     return new PhabricatorApplicationTransactionValidationError(
       $this->getTransactionTypeConstant(),
       $title,
       $message,
       $xaction);
   }
 
   final protected function newRequiredError($message, $xaction = null) {
     return $this->newError(pht('Required'), $message, $xaction)
       ->setIsMissingFieldError(true);
   }
 
   final protected function newInvalidError($message, $xaction = null) {
     return $this->newError(pht('Invalid'), $message, $xaction);
   }
 
   final protected function isNewObject() {
     return $this->getEditor()->getIsNewObject();
   }
 
   final protected function isEmptyTextTransaction($value, array $xactions) {
     foreach ($xactions as $xaction) {
       $value = $xaction->getNewValue();
     }
 
     return !strlen($value);
   }
 
   private function isTextMode() {
     $target = $this->getStorage()->getRenderingTarget();
     return ($target == PhabricatorApplicationTransaction::TARGET_TEXT);
   }
 
+  final protected function newRemarkupChange() {
+    return id(new PhabricatorTransactionRemarkupChange())
+      ->setTransaction($this->getStorage());
+  }
+
 }