  This paper gives an overview of notations used in multiway array processing.
We redefine the vectorization and matricization operators to comply with some
properties of the Kronecker product. The tensor product and Kronecker product
are also represented with two different symbols, and it is shown how these
notations lead to clearer expressions for multiway array operations. Finally,
the paper recalls the useful yet widely unknown properties of the array normal
law with suggested notations.
