AIA Document A401®–2017 establishes the contractual relationship between the contractor and subcontractor. It sets forth the responsibilities of both parties and lists their respective obligations, which are written to parallel AIA Document A201®–2017, General Conditions of the Contract for Construction, which A401–2017 incorporates by reference. A401–2017 may be modified for use as an agreement between the subcontractor and a sub-subcontractor, and must be modified if used with AIA Document A104™–2017 or A105™–2017 as the owner/contractor agreement.