A more thorough explanation:

ad quod damnum

Ad quod damnum is a legal term that means "to what damage." It refers to a writ that directs the sheriff to ask jurors under oath about the potential harm that would be caused by a grant, such as a fair, market, liberty, or other franchise, if the king were to make the grant. This writ was issued from the court of chancery.

An example of ad quod damnum would be if a king wanted to grant a new market to a town. The sheriff would then ask jurors under oath about the potential harm that would be caused by the new market, such as if it would harm existing businesses or cause traffic problems.

Another example would be if a king wanted to grant a new liberty to a group of people. The sheriff would then ask jurors under oath about the potential harm that would be caused by the new liberty, such as if it would infringe on the rights of others or cause public disturbances.

These examples illustrate how ad quod damnum was used to assess the potential harm that could be caused by a grant before it was approved.