Hooks let you change any of the messages displayed by Liferay to suit your needs. To do so, create a Language file for the locale of the messages you want to customize, then refer to your file from your liferay-hook.xml file. For example, to override the Spanish and French message translations of portal’s Language.properties file, create Language files for them in the same directory and refer to these language files in your liferay-hook.xml file, like this:
Tip: Check the DTD of each Liferay XML file, you modify for the elements and attributes that can be included in the XML and the specified order for those elements. You can find the Liferay DTDs online here: http://docs.liferay.com/portal/6.2/definitions.
Great! You now know how to customize language keys. Next, let’s discuss extending your Indexer Post Processor.