--- /dev/null
+<?php
+
+namespace Drupal\Core\Block;
+
+/**
+ * The interface for "title" blocks.
+ *
+ * A title block shows the title returned by the controller.
+ *
+ * @ingroup block_api
+ *
+ * @see \Drupal\Core\Render\Element\PageTitle
+ */
+interface TitleBlockPluginInterface extends BlockPluginInterface {
+
+ /**
+ * Sets the title.
+ *
+ * @param string|array $title
+ * The page title: either a string for plain titles or a render array for
+ * formatted titles.
+ */
+ public function setTitle($title);
+
+}