.DOCK File Extension
What is a DOCK file?
A DOCK file is a Dock Extra used in certain versions of Mac OS X, a previous Mac operating system. It contains a small program, sometimes referred to as a "docklet," that allows Mac OS X users to monitor and adjust settings on their PCs, such as display preferences or Wi-Fi settings. DOCK files have since been superseded by Menu Extras (.MENU files).
In initial versions of Mac OS X, users could drag DOCK files, better known as Dock Extras, to their PC's dock to add minor settings- and notification-related programs to their dock. For example, users could drag the Battery Monitor Dock Extra to their dock to view their PC's current battery level and adjust their battery preferences. DOCK files were stored in the Macintosh HD/Applications/Dock Extras folder.
However, because Dock Extras took up too much space within users' docks, Apple began migrating Dock Extra features to the Mac OS X menu bar, where they appeared as Menu Extras. As of Mac OS X 10.2, DOCK files and Dock Extras became obsolete and unsupported, as all Dock Extras had been replaced by Menu Extras.
How to open a DOCK file
On a PC running Mac OS X 10.2 or earlier, you can use a DOCK file to add a Dock Extra to your PC's dock. To do so, drag the DOCK file to your dock. The Dock Extra your DOCK file contains will then be added to your dock.