--- /dev/null
+<?php
+
+namespace Drupal\entity_browser\Events;
+
+/**
+ * Contains all events thrown by entity browser.
+ */
+final class Events {
+
+ /**
+ * The SELECED event occurs when enities are selected in currently active
+ * widget.
+ *
+ * @var string
+ */
+ const SELECTED = 'entity_browser.selected';
+
+ /**
+ * The DONE event occurs when selection process is done. While it can be emitted
+ * by any part of the system that will usually be done by selection display plugin.
+ *
+ * @var string
+ */
+ const DONE = 'entity_browser.done';
+
+ /**
+ * The REGISTER_JS_CALLBACKS collects JS callbacks that need to be notified when
+ * we bring selected entities back to the form. Callbacks are responsible to
+ * propagate selection further to entitiy fields, etc.
+ *
+ * @var string
+ */
+ const REGISTER_JS_CALLBACKS = 'entity_browser.register_js_callbacks';
+
+ /**
+ * The ALTER_BROWSER_DISPLAY_DATA allows for entity browser display plugin data
+ * to be tweaked.
+ *
+ * @var string
+ */
+ const ALTER_BROWSER_DISPLAY_DATA = 'entity_browser.alter_browser_display_data';
+
+}