--- /dev/null
+<?php
+
+namespace Drupal\metatag_open_graph\Plugin\metatag\Tag;
+
+use Drupal\metatag\Plugin\metatag\Tag\MetaPropertyBase;
+
+/**
+ * Provides a plugin for the 'og:image:alt' meta tag.
+ *
+ * @MetatagTag(
+ * id = "og_image_alt",
+ * label = @Translation("Image 'alt'"),
+ * description = @Translation("A description of what is in the image, not a caption. If the page specifies an og:image it should specify og:image:alt."),
+ * name = "og:image:alt",
+ * group = "open_graph",
+ * weight = 15,
+ * type = "string",
+ * secure = FALSE,
+ * multiple = FALSE,
+ * absolute_url = FALSE
+ * )
+ */
+class OgImageAlt extends MetaPropertyBase {
+ // Nothing here yet. Just a placeholder class for a plugin.
+}