Pete Daoust
The LEGAL definition of undertaking:
Undertaking
A written promise offered as security for the performance of a particular act required in a legal action.
In a criminal case, an undertaking of bail is security for the appearance of the defendant. In the event the defendant fails to appear, the amount posted as bail is forfeited.
An undertaking with adequate security is a bond. The term is used in a general sense to refer to any type of promise or stipulation.