tkdiff 4.1.3

tkdiff program is a merge tool and a graphical diff that runs under Unix, Mac OSX and Windows.
It provides a side-by-side view of the differences between two files, along with several innovative features such as diff bookmarks and a graphical map of differences for quick navigation.
The diff program was developed in the early 1970s on the Unix operating system which was emerging from AT&T Bell Labs in Murray Hill, New Jersey. The final version, first shipped with the 5th Edition of Unix in 1974, was entirely written by Douglas McIlroy. This research was published in a 1976 paper co-written with James W. Hunt who developed an initial prototype of diff.
McIlroys work was preceded and influenced by Steve Johnsons comparison program on GECOS and Mike Lesks proof program. Proof originated on Unix and produced line-by-line changes like diff and even used angle-brackets (">" and "<") for presenting line insertions and deletions in the programs output. The heuristics used in these early applications were, however, deemed unreliable. The potential usefulness of a diff tool provoked McIlroy into researching and designing a more robust tool that could be used in a variety of tasks but perform well in the processing and space limitations of the PDP-11s hardware. His approach resulted from collaboration also with individuals at Bell Labs including Alfred Aho, Elliot Pinson, Jeffrey Ullman, and Harold S. Stone.
In the context of Unix, the use of the ed line editor provided diff with the natural ability to create machine-usable "edit scripts". These edit scripts, when saved to a file, can, along with the original file, be reconstituted by ed into the modified file in its entirety. This greatly reduced the space necessary to maintain multiple versions of a file. McIlroy considered writing a post-processor for diff where a variety of output formats could be designed and implemented, but he found it more frugal and simpler to have diff be responsible for generating the syntax and reverse-order input accepted by the ed command. In 1985, Larry Wall composed a separate utility, patch, that generalized and extended the ability to modify files with diff output.
In diffs early years, common uses included comparing changes in programming language source code, source to technical documents, verifying program debugging output, comparing filesystem listings and analyzing computer assembly code. The output targeted for ed was motivated to provide compression for a sequence of modifications made to a file. The Source Code Control System (SCCS) emerged in the late 1970s as a direct consequence of this development.
A conceptual predecessor of diff includes Project Xanadu, a hypertext project established in 1960 that had envisioned a version tracking system necessary for its "transpointing windows" feature. As part of this feature, file differences were subsumed in the expansive term "transclusion", when a document has included in it parts of other documents or revisions.
In the digital realm of the humanities, computer comparison systems were understood to have been created for working on literary works published as large volumes.
Enhancements:
- This release fixes an incompatibility with older versions of Tcl/Tk, and improves Subversion support.