The property which is subject to a lien. A creditor with rights in collateral is a secured creditor and has additional protections in the Bankruptcy Code for the claim secured by collateral. The measure of the secured claim is the value of the collateral available to secure the claim: it is possible to have a lien on property that is subject to a senior lien or liens such that the security available to pay the claim is really without value to the junior creditor. The general rule with respect to liens is “First in time, first in right.”