[ENH] Added ZugferdSpecificationVersions to get the latest used speci…

…fication versions

src/ZugferdSpecificationVersions.php

@@ -0,0 +1,37 @@
+<?php
+
+/**
+ * This file is a part of horstoeko/zugferd.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace horstoeko\zugferd;
+
+/**
+ * Class representing the information source of the used specification versions
+ *
+ * @category Zugferd
+ * @package  Zugferd
+ * @author   D. Erling <horstoeko@erling.com.de>
+ * @license  https://opensource.org/licenses/MIT MIT
+ * @link     https://github.com/horstoeko/zugferd
+ */
+class ZugferdSpecificationVersions
+{
+    /**
+     * The latest ZUGFeRD version used
+     */
+    const VERSION_ZUGFERD = "2.3.2";
+
+    /**
+     * The latest Factur-X version used
+     */
+    const VERSION_FACTURX = "1.07.2";
+
+    /**
+     * The latest XRechnung version used
+     */
+    const VERSION_XRECHNUNG = "3.0.2";
+}