- contiguous rows; this is the order returned by
- \code{\link{read.tree}}. In the \code{"pruningwise"} order, rows are
- arranged so that ``pruning'' the tree (or post-order tree traversal)
- can be done by descending along the rows of `edge'. The possible
- multichotomies and branch lengths are preserved.
+ contiguous rows. In the \code{"postorder"} order, the rows are
+ arranged so that computations following pruning-like algorithm the
+ tree (or postorder tree traversal) can be done by descending along
+ these rows (conversely, a preorder tree traversal can be performed by
+ moving from the last to the first row). The \code{"pruningwise"} order
+ is an alternative ``pruning'' order which is actually a bottom-up
+ traversal order (Valiente 2002). (This third choice might be removed
+ in the future as it merely duplicates the second one which is more
+ efficient.) The possible multichotomies and branch lengths are preserved.
+
+ Note that for a given order, there are several possible orderings of
+ the rows of `edge'.