The letter in which an agency and a client lock the terms of a shoot before it starts: date, hours, fee, what the work covers and what may be done with the pictures. It is the contract for that one job.
What belongs in it
Date, call time, length of the shift and how overtime is paid. The address, or at least the city. The fee for the day, as a number. Usage on its own line: where, for how long and on what territory the client may show the images. Payment terms and who pays.
Also what is actually being shot. “A shoot for the brand” without a description of the work means that on the day you may be asked for things you never agreed to.
Why usage is written separately
Because it is the other half of the money. A shooting day and the right to run the images nationwide for three years are different things and are priced differently — «Usage Rights, Plainly: Portfolio, Editorial, Commercial».
When you read it
Before the shoot. “We’ll sort it out on set” is what makes the numbers disagree afterwards, and there is nobody to argue with once the client has gone and the images are out.
If the job on the day is different
Stop and call your booker rather than deciding yourself. A longer shift, more looks, work that was not in the letter — all of it changes the price, and the agency changes it, not the model between frames.
If you have no agency
Write the letter yourself: the same points in an email, confirmed by the client’s reply, already function as an agreement — «Releases and Agreements: The Minimum Paper Kit».