I have implemented the CD functions, all of them 100% to the exact same behavior of Game Maker, and I tested everything very very thoroughly. The only difference is that ENIGMA has a higher accuracy with the milliseconds, eg. playback position would be reported as follows.
ENIGMA: 1346, 1380, 1632, etc.
Game Maker: 1000, 1000, 2000, etc.
This was the pull request.https://github.com/enigma-dev/enigma-dev/commit/ac2ceb4ed2760a82d23bd07fc734faf75222f0fd
Full documentation can be found on the Wiki.http://enigma-dev.org/docs/Wiki/Disk_Functions
The functions also utilize the same part of the Windows API the original Game Maker ones did, the Media Control Interface. The functions and drag and drop actions are available through the extension by the same name, simply enable the extension and the functions and drag and drop actions should become usable. Also note that these are Windows only.
Not that these functions were rather important just to make sure we don't leave as much as we possibly can deprecated, and nevertheless it is optional, and these old functions help ensure maximum compatibility.