The Apple Certified Desktop Technician (or ACDT) was a computer certification that verified the ability of a person to perform basic repairs and troubleshooting on Apple's desktop Macintosh computers. It has been superseded by the Apple Certified Macintosh Technician (or ACMT) certification, which combines the former desktop and portable qualifications into one.
References
Apple Certified Desktop Technician Wikipedia(Text) CC BY-SA