consent is a letter
hello, her some help,
A letter of consent is a letter that you write when you are giving another person permission to do something on your behalf, such as allowing a neighbor to take a car to college.
Children traveling alone or with one parent in some countries;
When you ask another person to do something for you that involves using valuable items, such as loaning them a car;
When you want someone to sign documents on your behalf or attend meetings on your behalf
There some samples in the net...
good luck,