Contacts often familiar with Cupertino, Calif.-based company's operating system plans say the Mac maker this week began distributing the first external builds of Mac OS X 10.4.5 Update, which weigh in at approximately 15MB.
Two of the most recent builds are rumored to have appeared as "Mac OS X 10.4.5 build 8H3" and "Mac OS X 10.4.5 build 8H5."
While the specific fixes and enhancements planned for the update are unknown, Apple is reportedly asking that its developers and partners put weight on Safari, Core Graphics intensive applications, Quartz Composer, and the Mac OS X Dock.
The company also reportedly asked that developers test networking, the Mac OS X crash report, File Sync, Software Update and the MSDOS File System.
Members of Apple's Developer Connection program could begin to receive their first pre-release distribution of Mac OS X 10.4.5 as early as Wednesday afternoon, contacts have said.
It's unclear when Apple has targeted the release of Mac OS X 10.4.5 Update. Earlier this month, the company update Mac OS X 10.4 "Tiger" to Mac OS X 10.4.4 to coincide with the release of the first Intel-based Mac systems: the iMac Core Duo and MacBook Pro.