Sense of $d(adz_i\otimes dz_j)$?

Question

Is $d(adz_i\otimes dz_j)$ having any sense ? Maybe you can see the tensor as a form valued as a form, but how do you know where you differentiate $a$ ? As $da\wedge dz_i\otimes dz_j$ or $dz_i\otimes da\wedge dz_j$ ?

Thanks for your answers.