I am applying for O-1 visa. The visa requirements say that I should submit an advisory opinion. What is an advisory opinion?

An Advisory Opinion, also known as “Consultation Letter,” is a letter from US peer group or labor or management organization regarding the nature of proposed work and how the O-1 beneficiary’s outstanding qualifications fits to that work. The advisory opinion should describe the beneficiary’s ability and achievements in the field of endeavor, describe the nature of the duties to be performed, and state whether the position requires the services of an alien of extraordinary ability, with details on how the assessment or evaluation was made. An advisory opinion must set forth a specific statement of facts which supports the conclusion reached in the opinion.