--- /dev/null
+<?php
+
+namespace Drupal\link;
+
+use Drupal\Core\Field\FieldItemInterface;
+
+/**
+ * Defines an interface for the link field item.
+ */
+interface LinkItemInterface extends FieldItemInterface {
+
+ /**
+ * Specifies whether the field supports only internal URLs.
+ */
+ const LINK_INTERNAL = 0x01;
+
+ /**
+ * Specifies whether the field supports only external URLs.
+ */
+ const LINK_EXTERNAL = 0x10;
+
+ /**
+ * Specifies whether the field supports both internal and external URLs.
+ */
+ const LINK_GENERIC = 0x11;
+
+ /**
+ * Determines if a link is external.
+ *
+ * @return bool
+ * TRUE if the link is external, FALSE otherwise.
+ */
+ public function isExternal();
+
+ /**
+ * Gets the URL object.
+ *
+ * @return \Drupal\Core\Url
+ * Returns a Url object.
+ */
+ public function getUrl();
+
+}