Name for diagonals of a matrix I am looking for the terms to use for particular types of diagonals in two dimensional matrices.  I have heard the longest diagonal, from top-left element and in the direction down-right often called the "leading diagonal".  
-What about the 'other' diagonal, from the top right going down-left?  Does it have a common name? 
-Any general name to use for any diagonal going top-left to bottom-right direction, not necessarily just the longest one(s)?  I am searching for a term to distinguish between these types of diagonals and the ones in the 'other' direction.  Preferably the term should not be restricted to square matrices.  

$\diagdown$ Major, Principal, Primary, Main; diagonal $\diagdown$ 
$\diagup$  Minor, Counter, Secondary, Anti-; diagonal $\diagup$ 
