First draft

src/OAI/Exception/InvalidFormatException.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\OAI\Exception;
+
+final class InvalidFormatException extends \Exception
+{
+    public function __construct()
+    {
+        $this->message = "The metadata format is not supported for this item.";
+        $this->code = 'cannotDisseminateFormat';
+    }
+}