--- /dev/null
+<?php
+
+namespace Drupal\Component\Gettext;
+
+/**
+ * Methods required for both reader and writer implementations.
+ *
+ * @see \Drupal\Component\Gettext\PoReaderInterface
+ * @see \Drupal\Component\Gettext\PoWriterInterface
+ */
+interface PoMetadataInterface {
+
+ /**
+ * Set language code.
+ *
+ * @param string $langcode
+ * Language code string.
+ */
+ public function setLangcode($langcode);
+
+ /**
+ * Get language code.
+ *
+ * @return string
+ * Language code string.
+ */
+ public function getLangcode();
+
+ /**
+ * Set header metadata.
+ *
+ * @param \Drupal\Component\Gettext\PoHeader $header
+ * Header object representing metadata in a PO header.
+ */
+ public function setHeader(PoHeader $header);
+
+ /**
+ * Get header metadata.
+ *
+ * @return \Drupal\Component\Gettext\PoHeader
+ * Header instance representing metadata in a PO header.
+ */
+ public function getHeader();
+
+}