The expl3 bundle provides an implementation of the LaTeX3 programmers’ interface, as a set of packages that run under LaTeX 2e. The interface provides the foundation on which the LaTeX3 kernel and other future code are built: it is an API for TeX programmers. The packages are are set up so that the LaTeX3 conventions can be used with regular LaTeX 2e packages.

All the files of the bundle are also available in the Subversion (SVN) repository of the LaTeX3 Project.

The bundle on CTAN is based on a snapshot of the SVN repository as of 2010-01-12.