Subversion

Subversion primarily refers to the covert undermining or destruction of an established system, such as a government or social structure, from within. It involves overturning traditional values, authority, or norms. Additionally, "Subversion" is a widely used open-source version control system (Apache Subversion/SVN).

Subversion provides:

Directory versioning: CVS only tracks the history of individual files, but Subversion implements a “virtual” versioned filesystem that tracks changes to whole directory trees over time. Files and directories are versioned.

True version history: Since CVS is limited to file versioning, operations such as copies and renames—which might happen to files, but which are really changes to the contents of some containing directory—aren't supported in CVS. Additionally, in CVS you cannot replace a versioned file with some new thing of the same name without the new item inheriting the history of the old—perhaps completely unrelated—file. With Subversion, you can add, delete, copy, and rename both files and directories. And every newly added file begins with a fresh, clean history all its own.

Atomic commits: A collection of modifications either goes into the repository completely, or not at all. This allows developers to construct and commit changes as logical chunks and prevents problems that can occur when only a portion of a set of changes is successfully sent to the repository.

Versioned metadata: Each file and directory has a set of properties—keys and their values—associated with it. You can create and store any arbitrary key/value pairs you wish. Properties are versioned over time, just like file contents.

Choice of network layers: Subversion has an abstracted notion of repository access, making it easy for people to implement new network mechanisms. Subversion can plug into the Apache HTTP Server as an extension module. This gives Subversion a big advantage in stability and interoperability, and instant access to existing features provided by that server—authentication, authorization, wire compression, and so on. A more lightweight, standalone Subversion server process is also available. This server speaks a custom protocol which can be easily tunneled over SSH.

Consistent data handling: Subversion expresses file differences using a binary differencing algorithm, which works identically on both text (human-readable) and binary (human-unreadable) files. Both types of files are stored equally compressed in the repository, and differences are transmitted in both directions across the network.

Efficient branching and tagging: The cost of branching and tagging need not be proportional to the project size. Subversion creates branches and tags by simply copying the project, using a mechanism similar to a hard link. Thus, these operations take only a very small, constant amount of time.

Hackability: Subversion has no historical baggage; it is implemented as a collection of shared C libraries with well-defined APIs. This makes Subversion extremely maintainable and usable by other applications and languages.