With the release of Disk Copy 6.1, Apple began transitioning all software releases (including online software archives) to a new packaging that will make downloading faster and easier. This packaging is a new type of disk image called New Disk Image Format, or NDIF. Disk images in NDIF format are compressed to save space and download time, and decompress transparently when they are in use. You can even mount and install software directly from NDIF disk images on the desktop instead of making floppy disks. The NDIF format also includes check sums which guarantee the data integrity of disk images. With Disk Copy 6.1 (or later), you can make your own NDIF disk images of folders or mounted disks.
Apple's goal is to provide strong assurances that any software packaged in a NDIF disk image is downloaded or otherwise transferred and installed correctly. Therefore, Apple will only support Disk Copy 6.1 (or later) or Disk Image Mounter 2.1 (or later) to access NDIF disk images and only support Disk Copy 6.1 (or later) to create NDIF disk images. If an Apple customer uses a different application to access or create NDIF images, Apple will be unable to provide support if any installation or usage problems occur.
Note: This does not apply to Disk Copy 4.2 format disk images, as its file format is published and available to third parties to implement. Apple however, does not endorse any specific third party application or utility for accessing software packaged in Disk Copy 4.2 format.
Disk Copy 6.1 (or later) or Disk Image Mounter 2.1 (or later) from Apple is the recommended applications to access all disk images released by Apple and the only supported applications to access NDIF disk images; Disk Copy 6.1 (or later) is the only supported application to create NDIF disk images.