High Quality Content by WIKIPEDIA articles! Labels in Mac OS are a type of seven distinct, colored parameters of metadata that can be attributed to files, folders and disks in the operating system. The labels were introduced in System 7 and were kept until the release of Mac OS 9. Mac OS X versions 10.0, 10.1 and 10.2 lacked the attribute, which was reintroduced in Mac OS X version 10.3, though not without criticism.