Higher Hypercascading Hyper Notation (HHpCHN) is the 15th part of HN.
An expression is of the form H_m<n,A>, where n is the base, m is the secondary base, and A is an array.
Definitions from HHCHN apply.
X{1} = X, X{2} = Y, X{3} = Z.
H_A<B,C> is the first H-function.
X_A<B,C> is the second H-function.
Y_A<B,C> is the third H-function, that means it uses X_A<B,C> instead of H_A<B,C>.
Z_A<B,C> is the fourth H-function, that means it uses Y_A<B,C> instead of H_A<B,C>.
If N is sequence array:
X{N}_A<B,C> is the H-function of X{N-1}_A<B,C>, that means it uses X{N-1}_A<B,C> instead of H_A<B,C>.
If N is limit array:
X{N}_A<B,C> is the H-function of....WIP.
To compare arrays, first compare the Ns inside of X{N}, and if they are the same then compare the A inside of X{N}_A<B,C>, and if they are the same then compare the B,C inside of X{N}_A<B,C>, and if they are the same, use HHCHN rules.