Section 13. (a) For the purpose of administering this chapter, the commissioner or any employee or other representative designated by the commissioner for the purpose, may enter, at all reasonable hours, every place where milk is being produced, stored, bottled or otherwise packaged, processed, sold or otherwise handled for sale or distribution. Any such person may also, at all reasonable hours, inspect and verify by reference to the actual operations and transactions all books and records relating to milk in any place within the commonwealth for the purpose of ascertaining facts required for proper administration of this chapter.

(b) All milk dealers required to be licensed under this chapter, their affiliates and subsidiaries shall from time to time furnish to the commissioner such information as he may by order, rule or regulation require, upon and in conformity to forms or reports approved and supplied by him for the purpose of enabling him to administer and enforce this chapter and the orders, rules and regulations made thereunder. All such reports shall be on oath or made under the penalties of perjury.

(c) Each milk dealer required to be licensed under this chapter shall permit any member, the commissioner or any representative designated for the purpose by him, at all reasonable hours, to enter any place occupied or controlled by such milk dealer where milk is produced, stored, bottled or otherwise packaged, pasteurized, processed, sold or otherwise handled. Each such dealer shall at all reasonable hours identify and make available to any such person all books and records relating to milk or to such milk dealer's business which are in his possession or custody or under his control, and permit such person to inspect and verify the same as provided in subsection (a).

(d) The information obtained by any inspection authorized or reports required by this chapter or by similar provisions of earlier law shall be treated as confidential and shall not be disclosed by any person except as may be required in the proper administration of this chapter; provided, however, that the commissioner may use such information together with other similar information, for compilation and publication of statistics of the milk industry in this commonwealth. Such statistics shall not contain the name of, or disclose, by inference or otherwise, information obtained from the books and records of any milk dealer.

(e) Except as to markets in which there is in operation and effect an order or regulation issued by the legally constituted authorities of the United States regulating the marketing of milk in such markets, and except as to markets in which there is in operation and effect an order issued by the commissioner regulating the marketing of milk in such markets upon a market-wide pool basis, each milk dealer required to be licensed under this chapter, except a milk dealer eligible for exemption under subsection (b) of section four, and except a milk dealer who is also a producer selling to consumers not more than fifty quarts of milk daily, shall, within such period as the commissioner by order, rule or regulation requires, but not later than ten days after the close of each delivery period with respect to milk or cream received by such milk dealer, file with the director, in detail and form approved by the commissioner, a report as follows:—

(1) The receipts at each plant from producers, including the quantity, if any, of his own production;

(2) The receipts at each plant from any other milk dealer, including a milk dealer who is also a producer;

(3) The respective quantities of milk which were sold, distributed or used within each market, including sales to other milk dealers, in each use classification established by the commission.

The commissioner shall compute for each such milk dealer who purchases or receives milk from producers on the composite or on a base rating plan the percentage of milk sold, distributed or used by him in each such use classification and, notwithstanding the provisions of subsection (d), shall announce by mail, postage prepaid, to all such milk dealers and to all milk producers associations within the commonwealth the results of such computation, and the minimum composite price, or minimum base and excess prices which on the basis of said report such milk dealer, pursuant to the orders, rules and regulations of the commissioner, is required to pay per hundredweight of milk containing three and seven-tenths per cent butter fat content, delivered to the plant of such milk dealer by producers during each delivery period.

Such announcement shall be made on or before the fifteenth day after the end of each delivery period. If any such milk dealer receives milk from producers at more than one plant subject to the provisions of this subsection, such percentage and such minimum price or prices shall be separately computed and announced by the director for each such plant.

The words ''delivery period'', as used in this subsection, shall mean, with respect to milk dealers who buy no milk from producers, a monthly period beginning on the first day of each month and, with respect to all other milk dealers, the delivery period applicable to such milk dealers as determined by order of the commissioner. The composite plan and base rating plan referred to in this subsection shall mean the composite plan and base rating plan as determined by order of the commissioner.

(f) Subsection (e) shall be construed as being in addition to and in no way limiting the power and authority of the commissioner under subsection (b).