It is confusing to know how a data cube is transposed given the
current transpose arguments.
The table shows along the horizontal the various invocations
for the Transp plane argument. The vertical list shows where
the given axis goes. For example Transp plane=21
switches the n1 and n2 axis but leaves n3 untouched.
13 12 23 31 32 21
n1 n3 n2 n1 n3 n1 n2
n2 n1 n1 n3 n1 n3 n1
n3 n2 n3 n2 n2 n2 n3
shift 1-2 2-3 shift 2-3 1-2