As used in this article:

1. (a) “Amount secured by the lien” includes interest and any costs and charges secured by the lien.
2. (b) “Encumbered property” means real or personal property that is subject to a lien for a secured debt which is a valid claim against the estate and which has been allowed or approved.
3. (c) “Lien” means a mortgage, deed of trust, or other lien.