This is the BBC, but as a N. American dishwasher user, I'm struggling to translate the advice on soap/detergent. "Table" and "salt" are two terms that aren't linked to dishwashers in the middle of N. America. We've got "pods" (bad, manufacture specifies how much soap to use, also kids eat them), and we've got rinsing agent. You get a little bottle of rinsing agent with your dishwasher, and you never put it in again. It's magic.

Why would I put "salt" in my dishwasher? The article makes that additive out as preventative maintenance, and I don't think that's true of sodium chloride.