Introduction Outline of the proof and summary The simple roots and reflections of $B_n$ and $C_n$ The $q$-engine of our $q$-machine Removing the denominators The $q$-transportation theory for $BC_n$ Evaluation of the constant terms $A,E,K,F$ and $Z$ $q$-analogues of some functional equations $q$-transportation theory revisited A proof of Theorem 4 The parameter $r$ The $q$-Macdonald-Morris conjecture for $B_n,B_n^\lor,C_n,C_n^\lor$ and $D_n$ Conclusion.