Reimbursement of expenses to the Contractor shall not include any of the following:

(a) Salary of the Contractor, if an individual, or salary of any member of the

Contractor, if a firm, or salary of any officer of the Contractor, if a corporation.

(b) Salary of any person employed, during the execution of the work, in the main office or in any regularly established branch office of the Contractor.

(c) Overhead or general expenses of any kind, except as these may be expressly included in Article 5.

(d) Interest on capital employed either in plant or in expenditures on the work, except as may be expressly included in Article 5.