This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
When a log of wood has been sawed up into boards, each board is apt to have along the edge a strip of the bark which was originally on the outside of the log, and the edges will not be square with the face of the board, owing to the cylindrical shape of the log. Such boards should be squared up by having the rough edges to which the bark adheres trimmed off. But sometimes the bark alone is stripped off, leaving the boards with the edges not square with the face. Such boards are said to be waney, and very often specifications state that no waney lumber shall be employed on the work. The pieces which are cut off when waney boards are trimmed in order to square them up are called "edging" and are used to make laths.