--- /dev/null
+<?php
+
+namespace Drupal\metatag_favicons\Plugin\metatag\Tag;
+
+use \Drupal\metatag\Plugin\metatag\Tag\LinkRelBase;
+
+/**
+ * The Favicons "mask-icon" meta tag.
+ *
+ * @MetatagTag(
+ * id = "mask-icon",
+ * label = @Translation("Icon: SVG"),
+ * description = @Translation("A grayscale scalable vector graphic (SVG) file."),
+ * name = "mask-icon",
+ * group = "favicons",
+ * weight = 2,
+ * type = "image",
+ * secure = FALSE,
+ * multiple = FALSE
+ * )
+ */
+class MaskIcon extends LinkRelBase {
+ // Nothing here yet. Just a placeholder class for a plugin.
+}
+