(a) At the time that it submits any periodic report to the Commission, the Postal Service shall identify any input data that have changed, list any quantification techniques that it has changed, and list any corrections that it has made since that report was last submitted to and accepted by the Commission. It shall provide a brief narrative explanation of each listed change.

(b) If workpapers are required to support a periodic report, they shall:

(1) Show all calculations employed in producing each estimate;

(2) Be sufficiently detailed to allow all numbers used in such calculations to be traced back to public documents or to primary data sources; and

(3) Be submitted in a form, and be accompanied by sufficient explanation and documentation, to allow them to be replicated using a publicly available PC application.

(c) Spreadsheets used in preparing periodic reports shall be submitted in electronic form. They shall display the formulas used, their links to related spreadsheets, and shall not be password protected.

(d) Filing of portions of the documentation required by paragraphs (b) and (c) of this section that are not time critical may be delayed up to 2 weeks if the Postal Service obtains permission from the Commission to defer filing of such portions at least 30 days prior to the date on which the periodic report is due.