Teradata tends to make a distinction between a join TYPE (INNER OUTER FULL OUTER CROSS) vs a join STRATEGY (MERGE HASH PRODUCT).
In this case CROSS & CARTESIAN are TYPEs and PRODUCT is the Strategy. Product joins can be chosen as within a PLAN's join GEOGRAPHY to include a product join at any suitable time, even on an INNER join.
EG: a large fact table with many dimentions - the optimiser might first product join all the dimention together and then INNER join the result back to the fact table. I've seen this happen many times.