This project uses Mercurial to manage its source code. Instructions on Mercurial use can be found at http://hgbook.red-bean.com/read/.
The source can be checked out anonymously from Mercurial with this command (See http://www.selenic.com/mercurial/hg.1.html#clone):
$ hg clone http://jeuclid.hg.sourceforge.net:8000/hgroot/jeuclid/jeuclid/jeuclid-mathviewer
Only project developers can access the Mercurial tree via this method (See http://www.selenic.com/mercurial/hg.1.html#clone).
$ hg clone ssh://jeuclid.hg.sourceforge.net/hgroot/jeuclid/jeuclid/jeuclid-mathviewer