The LaTeX extension witharrows is distributed under the LPPL 1.3 license.

This extension has been written by F. Pantigny (fpantigny@wanadoo.fr).

This extension is entirely contained in a single file : witharrows.sty

The extension witharrows gives a LaTeX environment {WithArrows} which is similar
to the environment {aligned} of amsmath but which gives the possibility to draw arrows 
on the right side of the equations for explanations.