Someone buy your name

Someone told me

If i make namespace and like

jasmine20.mynahost

and i pay 100 xem for it

if someone is interested in that name and i have the name but he-she want that name and offer more they become owner of the name

Thx for reading

They would have to buy the mosaic and the namespace, no idea how this happens.
It may be an amiable agreement or escrow service.
Good point though, how does ownership of a namespace and mosaic take place if there is a need to sell to another party?

There is no option to sell right now as far as I know. You can sell your private key. Maybe in catapult selling namaspaces will be possible.