All content that is crawled requires the use of a protocol handler to gain access to that content. Office SharePoint Server 2007 provides protocol handlers for all common Internet protocols. However, if you want to crawl content that requires a protocol handler that is not installed with Office SharePoint Server 2007, you must install the third-party or custom protocol handler before you can crawl that content.
The following table shows the protocol handlers that are installed by default.
Business Data Catalog
Business Data Catalog URLs (internal protocol)