+Create a file called ExtensionName.i18n.magic.php with the following contents:
+----
+<?php
+
+$magicWords = array();
+
+$magicWords['en'] = array(
+ // Case sensitive.
+ 'mag_custom' => array( 1, 'CUSTOM' ),
+);
+
+$magicWords['es'] = array(
+ 'mag_custom' => array( 1, 'ADUANERO' ),
+);
+----
+
+$wgExtensionMessagesFiles['ExtensionNameMagic'] = __DIR__ . '/ExtensionName.i18n.magic.php';