* @property integer parent Parent Item Id
* @property boolean seen Whether the notification was read or not.
* @property string verb Verb URL (@see http://activitystrea.ms)
- * @property string otype Subject type (`item`, `intro` or `mail`)
+ * @property string otype Subject type ('item', 'intro' or 'mail')
*
* @property-read string name_cache Full name of the contact subject
* @property-read string msg_cache Plaintext version of the notification text with a placeholder (`{0}`) for the subject contact's name.