the dentist's business pays taxes, he includes the bill endorsed by you as a claim against his payment by giving them the endorsed bill as applied to the payment. it is sort of like reverse withdrawal, he gives them the endorsed bill for credit as if it were a third party check. your signature offsets his debt.
Printed copy · Anthology Volume 3, page 514Printed copy from The Tender For Law Anthology, Volume 3, page 514 (printed 13 June 2014). Added by this site; not part of the Facebook export.