SVN
From Wesnoth
You may have heard the term "SVN" used somewhere like IRC chat or the forum. This page will explain what SVN means.
Short Answer
SVN means the most up-to-date version of the code, even more updated than the latest release.
It is the project's set of working files that have been edited since the last release came out.
For example, a bug can exist in release 1.3.x but fixed in SVN, meaning those changes will be published in the next official version.
Long Answer
SVN is shorthand for Subversion, which is the name of a computer program designed to manage a group of files that together make up a software project. Subversion can be obtained, installed, and run by anyone from the Subversion homepage. It is cross-platform Free software.
The Battle for Wesnoth code base is stored in a subversion repository stored on http://gna.org. Subversion allows the entire dev team to edit files simultaneously. The software tracks revisions, stores a record of all edits, and arbitrates simultaneous editing. All changes are stored in the subversion repository. The current state of the code base is referred to as SVN.
When a release is planned, the current set of the files in SVN is frozen, given a release number, and shipped out to the world at large. Then, as files continue to be edited by the developers, the SVN code advances past that point. The SVN version is by definition the most up-to-date version of the code.
You can browse Wesnoth's SVN repository online.
Subversion replaced an older program called "CVS" or "concurrent versioning system." SVN boasts more advanced control features and is gradually replacing CVS as the standard. CVS, in turn, had replaced RCS ("revision control system"), which is a unix/linux tool that does basically the same thing.