Updated datasource example code. Added links to formal protocols for the datasource and delegate.

Updated to note new formal protocol on OS X v10.6.

Clarified memory management for data source.

Added information to the section "About Outline Views."

Noted that Option-clicking an item’s disclosure triangle expands or collapses all of its contained items, and that an outline view can remember the expanded or collapsed state of contained items that were previously shown.

Noted that NSOutlineView requires that each item in the outline view be unique.

Changed the title of the article "Using an Outline View Data Source" to "Writing an Outline View Data Source."

Enhanced description of data source requirements and implementation in Writing an Outline View Data Source.

Revision history was added to existing topic. It will be used to record changes to the content of the topic.