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(Hierarchical File System) The previous file system in the Mac, which was replaced with the Apple File System (see APFS). The first version of HFS, known as "Mac OS Standard," was introduced in 1985. HFS+ ("Mac OS Extended") came out in 1998 in preparation for Mac OS X, featuring Unicode support and a dramatically increased file size from 2GB to 16TB. In 2003, journaling was added (see journaling file system), and case-sensitive file names were introduced under the HFSX option. Case-sensitive names are a standard feature of Unix, and Mac OS X is based on Unix (see Mac OS X).

Data and Resource Forks
The design of HFS departed from other file systems of that day with support for two types of structures: the "data fork" and "resource fork." The data fork is like other file system structures. Data are accessed by an offset into the file; for example: OPEN FILE and READ FROM BYTE 13,904.

The resource fork functions like a mini-database, holding executable code and program structures such as icons, menus and sounds. Instead of storing an executable program as a monolithic block, having the program's resources in separate structures allows them to be edited independently and more easily localized into different languages. In addition, data files can use the two forks with the resource fork acting as a sub-file system. For example, a word processor would naturally have its text in the data fork, but could store images in the resource fork. See APFS, file system and hierarchical file system.
References in periodicals archive ?
Our place in HfS Winners Circle acknowledges our significant expertise in achieving strong business outcomes for our clients, said Shantanu Ghosh, senior vice president, CFO Services and Consulting, Genpact.
Evidence exists that supports the use of HFS as an effective and preferred training method for critical care training.
Paul Pinto, Managing Partner of Sylvan Advisory, who joins HfS Consulting as Executive Vice President, commented, "The formation of HfS Consulting represents a truly unique combination of very deep, ground-level, experience, that is based on relevant and unbiased market research.
Nehring, Lashley, and Ellis (2002) described how HFS can be used throughout a nursing curriculum, beginning with basic assessment skills and progressing to the integration of different competencies in complex patient care situations.
Wipro is one of the strongest SAP service providers globally and HFS recommends Wipro must be on the shortlist for large SAP projects.