How should my esa-systems probe or nozzle be aligned?

Both in practice as well as in literature, one sees again and again probes and nozzles installed with the TE head in a downwards position, but the correct way is with the TE head pointing upwards!
The only two exceptions are esa-systems probes of type DN/ : these probes have two TE measurement points pointing sideways and have to be aligned parallel to the wings in order to return precise measurements. And in case the vertical stabilizer has two mounting adapters installed, the probes need to be oriented so that they may not influence each other.