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#REDIRECT [[Apple Disk Image#History]]
{{Cleanup|date=June 2011}}
'''UDIF''' stands for '''Universal Disk Image Format'''. It is used on [[Mac OS X]] for [[.dmg]] [[disk image]]s. UDIF is a flat [[file format]], and is the [[Native and foreign format|native image format]] for Mac OS X.
The format can also be opened by [[MagicISO]] and the [[freeware]] MagicDisc on [[Microsoft Windows|Windows]].
==Universal Disk Image Header==
The header can be described using the following C structure. All values are little-endian ('''Apple II''' byte ordering)
{| class="wikitable"
|-
! Position(in Hex) !! Length (in bytes) !! Description
|-
| 000 || 4 || The integer constant '2IMG'. This integer should be little-endian, so on the Apple IIgs, this is equivalent to the four characters 'GMI2'; in ORCA/C 2.1, you can use the integer constant '2IMG'.
|-
| 004 || 4 || A four-character tag identifying the application that created the file.
|-
| 008 || 2 || The length of this header, in bytes. Should be 52.
|-
| 00A || 2 || The version number of the image file format. Should be 1.
|-
| 00C || 4 || The image format.
|-
| 010 || 4 || Flags
|-
| 014 || 4 || The number of 512-byte blocks in the disk image. This value should be zero unless the image format is 1 (ProDOS order).
|-
| 018 || 4 || Offset to the first byte of the first block of the disk in the image file, from the beginning of the file. The disk data must come before the comment and creator-specific chunks.
|-
| 01C || 4 || Length of the disk data in bytes. This should be the number of blocks * 512.
|-
| 020 || 4 || Offset to the first byte of the image comment. Can be zero if there's no comment. The comment must come after the data chunk, but before the creator-specific chunk. The comment, if it exists, should be raw text; no length byte or C-style null terminator byte is required (that's what the next field is for).
|-
| 024 || 4 || Length of the comment chunk. Zero if there's no comment.
|-
| 028 || 4 || Offset to the first byte of the creator-specific data chunk, or zero if there is none.
|-
| 02C || 4 || Length of the creator-specific chunk; zero if there is no creator-specific data.
|-
| 030 || 16 || Reserved space; this pads the header to 64 bytes. These values must all be zero.
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==External links==
{{R from merge}}
* [http://developer.apple.com/documentation/Darwin/Reference/ManPages/man1/hdiutil.1.html <tt>man</tt> page for hdiutil]
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* [http://www.magiciso.com/ Main page for magic ISO]
[[Category:Computer file formats]]
[[Category:Mac OS X]]
[[Category:Disk images]]
Universal Image Format(UIF) is a powerful compression image file format for backing up CD/DVD. It is fast, reliable, and has rich set of features which include password-protected, data encryption, MD5 checksum support and much more. UIF can not only contain the complete data of CD/DVD just like ISO image, But UIF also supports backuping multi-session CD/DVD, Audio-CD, VCD, SVCD and DVD-Video.
What is the advantage to use UIF instead of ISO Image, zip, rar and other CD/DVD image to backup CD/DVD? The first and important advantage of using UIF is that can reduce the size of image file, it saves both in the compression and in the saving of disk sector cluster, UIF is a compressed format, It compresses raw CD/DVD data with high quality compression-method. Second, You can backup secret and private CD/DVD using UIF. Especially, It has the advantage to transfer CD/DVD through the Internet. UIF provides both the feature of password-protected for denying the access from any unauthorized user and other feature of data encryption for defeating any sniffer and hacker. Easy and Express to use UIF without restoring and extracting. Unlike ZIP,RAR and other compression archive, you don't have to extract files and folders from UIF before you need to use this files or folders. Just use virtual CD/VD software like MagicDisc to mount UIF image as virtual CD so that you can access all files and folders in UIF image through this virtual CD just like accessing your the original CD/DVD.! also used on macs
{{Disk images}}
{{mac-stub}}
[[it:Universal Disk Image Format]]
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