Lien releases

are often required by contract, and generally require the parties to the contract to give up their lien rights entirely

are often required by contract, and can be used by the owner to delay payment to subcontractors are often required by contract, and entirely stop liens from being filed on a project

are often required by contract, and generally release lien rights related to the work the contractor $($Prime$,$ oub, or lower tier$)$ has already been paid for