It’s an asset with zero value. They still own it and retain all rights, they just think it’s worth $0. This is very important for tax purposes as if they ever

It’s an asset with zero value. They still own it and retain all rights, they just think it’s worth $0. This is very important for tax purposes as if they ever sell it then they will pay taxes on the full amount sold. If they had a value on books then they would pay the difference of the sales price vs the value on books.