The package allows the construction of proof trees in the style of the sequent calculus and many other proof systems. One novel feature of the macros is they support the horizontal alignment according to some centre point specified with the command \fCenter. This is the style often used in sequent calculus proofs.

The package works in a Plain TeX document, as well as in LaTeX; an exposition of the commands available is given in the package file itself.

The author is Sam Buss. The package is Copyright © 1994-1996,2004-2006 Samuel R. Buss.