Current and accrued assets are cash, those assets which are readily convertible into cash or are held for current use in operations or construction, current claims against others, payment of which is reasonably assured, and amounts accruing to the service company that are subject to current settlement, except those items for which accounts other than those designated as current and accrued assets are provided. There must not be included in the group of accounts designated as current and accrued assets any item, the amount or collectibility of which is not reasonably assured, unless an adequate provision for the related possible loss has been made. Items of current character but of doubtful value may be written down and for record purposes carried in these accounts at nominal value.