Keynote's XML Connections
Subject:   First XML document
Date:   2003-11-20 11:28:08
From:   chixulub
Response to: First XML document

Most Cocoa applications store their preference files as .plists in XML format. But these files do not contain information that is edited in an application; most of the time they are used for preferences. Applications like iTunes and iPhoto provide XML files that mirror the information stored in their libraries, but the libraries themselves use a binary format.

I'm sorry the distinction wasn't more clear in the article.