AIA Document A401™–2007 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™–2007, General Conditions of the Contract for Construction, which A401–2007 incorporates by reference. AIA Document A401 may be modified for use as an agreement between the subcontractor and a sub-subcontractor, and must be modified if used where AIA Document A107™–2007 or A105™–2007 serves as the owner/contractor agreement.