Ditto, no clue what either of those mean. Never, ever heard of adding salt to a dishwasher, certainly. Not in new ones, not in ones from the bad ol' days when they used way more water but actually worked.
I have a new one (a few years old) and yes there's a compartment for salt. My previous one did as well. I'm in Europe (Spain) if that helps. I don't go to any special store to buy them, any old Lidl or other supermarket has it. Where you from where this isn't a thing?
From other comments it's looking like this one of those US/European divide things, with compartments for salt being uncommon on US dishwashers except for a few rare higher-end models/brands that are likely common to both continents (due to low volume in the US not justifying a localized version, I'd guess). I'm middle-aged and in the US and this thread is the first time I've heard of adding salt to a dishwasher.
Really odd that it differs so close to neighbouring countries. Here (UK) I've never seen a Dishwasher without a salt hole, and there's often several well know brands of salt in the supermarket (no idea why, its all the same stuff).
I wonder if its based on average water hardness in the area. I'm in the north of England and our supply comes out of Buxton Springs (yep the same as Buxton bottled water) and is extremly soft so despite filling the salt it never asks for it to be refilled again as its not needed.
When I used to live in north London I'd be filling it up once a month as the water there is extremely hard - so hard that it'll kill your kettle within a year if you don't keep on top of descaling.
In the US you would install a house water softener that would soften the water when it comes into the house. It would only be used in areas with hard water. Our dishwashers usually use hot water rinses instead of cold water like European style ones, the hot water heaters will soft the water before it gets to the appliance.
Anecdotes are not data and all that. The dishwasher in my house is a NEFF, and it has a salt compartment. Came with the house, built-in unit. So yes, some Irish houses have dishwashers with salt - sample size 1.
