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| Glossary
Term |  | Definition
AES Crypt (128-bit) |  | Encryption provided by the Advanced Encryption Standard to secure disk images with a passphrase.
bzip2 |  | A newer file compression utility that can compress files more effectively, but more slowly than gzip.
Checksum |  | Attempt to determine the integrity of disk images, or volumes by comparing a pre-calculated sum of the correct digits of data with a current sum.
Compact |  | Compact the freespace in a SPARSE type disk image, removing those parts that are no longer being used by the filesystem. Depending on the organization of files in the filesystem, compact may or may not shrink the image file.
Compression |  | The process of encoding information using fewer bits than the unencoded representation.
Convert |  | Convert an image to the specified type (Read-Only, Read/Write, etc.).
Disk Copy |  | A classic Mac OS application that allowed users to copy, restore from, and manipulate disk image (.img) files.
Disk Image |  | A virtual disk flat-file format utilized in Mac OS X for the distribution of software installers, bootable CD images, and many other important technologies like Netboot.
Encryption |  | The process of transforming information using an algorithm (or cipher) to make it unreadable to anyone except those possessing special knowledge (referred to as a "key").
File System |  | A format that is used in conjunction with disks to create a store for data on computer systems.
Flatten image |  | Flatten a read-only or compressed UDIF disk image into a single-fork file.
Format |  | Different types of formats exist for disks on different operating systems. Mac OS X uses the HFS+ format or filesystem, while Windows uses the NTFS or FAT32 filesystems for native disks.
Get info |  | Show information about the disk image in the log view.
gzip |  | The GNU free software file compression program, which can compress data onto the gzip file format.
HFS |  | The classic Mac OS volume format supported volumes up to 2 GB in Mac OS 8 and 9.
HFS+ |  | The Mac OS Extended volume format provides support for volumes up to 16 TB in Mac OS 10.3 and greater.
HFSX |  | Another version of HFS+ that does not have an HFS wrapper, and supports case sensitivity.
Hybrid image |  | A image that can represent optical media such as CDs and DVDs. These images can be mounted on most modern computing platforms, including BSD, Linux, Mac OS X, and Windows.
Image on the fly |  | A method of disk imaging in FreeDMG that allows the user to quickly image a dropped folder or file without having the software prompt for information on how to create the image. Image options are derived from preferences.
Internet enabled disk images |  | An internet enabled disk image allows web browsers such as Safari to automatically mount downloaded disk images, and copy the image's contents to the location that it was downloaded to, discarding the image afterwards.
Journaled HFS+ |  | A volume format introduced in Mac OS 10.2.2 was the Journaled HFS+ format, which provides increased data reliability.
MS-DOS (filesystem) |  | The FAT16 volume format as implemented in Mac OS X.
Mount |  | Mount a disk image or volume. Mounted disk images appear on the desktop by default.
NDIF |  | An acronym for "New Disk Image Format" - this was the default format of disk images in the classic Mac OS.
Overwrite existing files |  | If a file with the same name as an image that is being created exists at the destination path, it will be overwritten.
Password Encrypted |  | Use a passphrase to encrypt the disk image. The disk image will require that the passphrase be provide each time a user attempts to mount it (the user can choose to save the passphrase in their Mac OS keychain).
Quit after imaging (on launch) |  | This option allows the user to have FreeDMG quit itself if it was launched by having a folder(s) or file(s) dropped onto its icon.
Resize |  | Resize the volume that exists within a disk image. The volume can only be resized to the limits that are applied to the encompasing disk image. Sparse images can be used to create images that automatically adapt to the resizing of the volumes inside.
Scan for restore |  | This option prepares an image for block restore using "asr" or other tools in 10.4. In 10.3, the "Scan Image for Block Restore" must be chosen for block copy restore, and "Scan Image for Restore" to prepare the image for file copy restore.
Scrub Image |  | The process of removing temporary filesystem data from sources before creating images - this includes trashes, temporary directories, swap, .DS_Store, etc.
Segment |  | Divide a disk image into multiple parts. Segmented disk images must have all segments intact, and reside in the same folder as the rest of the segments when mounting.
Software License Agreement |  | A software license agreement binds a user to terms under which the software can be used. Generally, this license is presented before the first use of the software. Using FreeDMG, SLAs can be attached so that the user must agree to the terms of the provided license before gaining acess to the software.
Sparse Bundle |  | Similar to a sparse image, this bundle-style disk image incorporates informational plist files and sparse disk images into a single package. Sparse Bundles are used by FileVault in Mac OS X v.10.5.
Sparse image |  | A type of disk image that automatically resizes with the volume inside of it.
UDIF |  | An acronym for "Universal Disk Image Format" - the default format of disk images in Mac OS X.
UFS |  | UNIX File System - a volume format that is used in may unix and unix-like operating systems.
Unflatten image |  | Unflatten a read-only or compressed UDIF disk image, creating a dual-for file in traditional format.
Verbose logging |  | Provide more information than is normally displayed in the log window.
Verify |  | Verify the integrity of a disk image or volume.
Volume |  | A logical filesystem created on a physical disk, or inside of a disk image.
Volume Format |  | See Format
128-bit |  | This level of encryption specifies that the key width is 128 bits wide. This allows for fairly secure protection of data (and is the modern standard for data encryption).
256-bit |  | A higher level of encryption (compared to 128-bit) that provides very secure protection of data. The key size for this symmetric cipher is 256 bits wide.