The default setting is the commission is sent via the
API. This makes things quite flexible as you
can set whatever percentage you want for individual sale products before sending it to the affiliate system.
If you set a commission value here, the commission value from the
API will be ignored and the
system will auto calculate the percentage based on the sale total sent by the
API. This is useful if you want to give certain affiliates a higher percentage earning. If a commission is set here, it would apply to all sales for any product.