Hard to draw ASCII here, but imagine a symlink from "/js/jquery.js" pointing to "/js/jquery-1.2.3.js".
A good application will write output that has a literal copy of the numbered version, and a symlink point to it.
Bad applications either ignore symlinks entirely, or change them to duplicate copies of files. (Which can be bad if you're considering a large file such as foo-latest-release.tar.gz.)