Even if you could book them at par, you’d need to write them down when the due date came and they didn’t pay off, unless the regulators were directed to cut you some slack. And what is the value of a nonnegotiable instrument which is in default. Even with ‘mark to model’ instead of ‘mark to market’ you’d have a hard time making those look good.
If the paper does not have a maturity date and you cannot redeem it on demand - what is it really worth? Zero?