What is the purpose of a "stop payment notice" on a private construction project?

Explanation

A stop payment notice reaches money rather than land. §8520(a) lets any claimant with lien rights other than the direct contractor give the owner such a notice, §8530 lets the same claimant give one to the construction lender, and §8500 makes this chapter the exclusive route to the construction fund: no person may assert any other legal or equitable right against that fund except under a written contract with whoever holds it. §8044(a) adds that the notice may be bonded or unbonded, and a bonded notice is what compels a lender to withhold. (b) confuses it with a stop order, which Cal/OSHA or the registrar issues against the use of employee labour; nothing in a stop payment notice halts construction. (c) is the mechanics lien, the parallel remedy that does attach to the property. (d) sends the notice to an office with no role in the payment chain. §8520(b) is the trap running the other way: if the owner demands a stop payment notice and the claimant fails to give one, the claimant forfeits its lien.