Nexum was a debt bondage contract in the early Roman Republic. The debtor pledged his person as collateral should he default on his loan. Nexum was abolished by the Lex Poetelia Papiria in 326 BC. Nexum was a form of mancipatio, a symbolic transfer of rights that involved a set of scales, copper weights, and a formulaic oath. Under the nexum contract, a free man became a bond slave, or nexus, until he could pay off his debt to the creditor, or obaeratus. Varro derives the word nexum from nec suum, "not ones own," and although this etymology is incorrect in light of modern scientific linguistics, it illuminates how the Roman understood the term. It remains unclear whether debtors entered into a nexum contract initially with their loan or if they entered voluntarily after they could not pay off an existing debt, though the former seems more likely to be the case. Additionally, there is no single formal nexum contract that all nexi entered – it is possible that there were many variations of the nexum contract, and that the details of nexum contracts were worked out on a case-by-case basis.