Interaction term in Cox PH model

[CHELS]

Hello experts,

I have one question regarding interaction term. Let's say I have two dichotomous variables A and B. What is the difference between using an interaction term A*B in the model vs. creating a grouping variable that has four levels (A+B+; A+B-; A-B+; A-B-)?

Thanks!

[data_null__]

Test it.

[Ksharp]

No difference .Both have the same design matrix.

Maybe @StatDave  @SteveDenham @lvm  @Rick_SAS  know something .