Air carrier Captain reported explosives and a power source were packaged together as Dangerous Goods. The Captain had the DG cargo removed prior to departure.

Narrative

Using Captain Authority; I refused Dangerous Goods (DG) described as explosives and power source that were packaged together. Everyone was cooperative and understood the nature of the refusal. One thing we are not trained on is how the Captain can tell the DG was removed from paperwork in addition from the verbal from Ramp. I learned a new DG message is sent and the Position of the DG will say 'OFF'. I wish there is a Code for DG refusal opposite the acceptance code.