The goldsmith might also write notes promising so much gold and not promising the return of any particular item of gold.

这个金匠会写下票据,保证归还一定数量的金子,但是不保证归还某个特定的金器

耶鲁公开课 - 金融市场课程节选

So, the goldsmith would sign his name on it saying, I promise to give so many ounces of gold.

所以这个金匠会在票据上签名,保证归还多少盎司的金子

耶鲁公开课 - 金融市场课程节选