39 C.F.R. § 3010.125 – Library references.

(a) In general. A library reference is a special type of filing, which is accepted by the Commission for the convenience of the person filing material that is not conducive to typical text based filings. The filing of a document as a library reference is appropriate when interest in the material is limited, when the material constitutes a secondary source that provides background or support for a position or matter, or when references to, or identification of, the material filed as a library reference would be facilitated. Examples of materials that are appropriate for filing as library references include electronic spreadsheets, workpapers in support of primary documents, pre-existing materials, secondary sources such as books or materials that are not readily available elsewhere, or other foundational materials filed in support of a primary document. Whenever possible, library references are to be filed in electronic format. The Commission reserves the right to refuse acceptance of any library reference material in its docket room and its right to take other action to ensure all persons' ability to obtain access to the material.
(b) Categorization of library references. To the extent possible, material filed as a library reference shall be identified and referred to by participants in terms of the following categories:
1. (1) Category 1—Reporting Systems Material (consisting of library references relating to the Postal Service's statistical cost and revenue reporting systems, and their primary outputs);
2. (2) Category 2—Witness Foundational Material (consisting of material relating to the testimony of specific witnesses, primarily that which is essential to the establishment of a proper foundation for receiving into evidence the results of studies and analyses);
3. (3) Category 3—Reference Material (consisting of previously published material provided for the convenience of the reader, such as books, chapters or other portions of books, articles, reports, manuals, handbooks, guides, and contracts);
4. (4) Category 4—Material Provided in Response to Discovery (consisting of material provided in response to discovery requests);
5. (5) Category 5—Disassociated Material (consisting of material filed at the request of another, from which the filing party wishes to be disassociated, is not vouching for or sponsoring the material provided);
6. (6) Category 6—All Other Material (consisting of library references not fitting any of the other categories).
(c) Labeling. Material filed as a library reference shall be labeled in a manner consistent with standard Commission notation and any other conditions the Commission or presiding officer establishes. Each library reference shall be identified by a unique identification number. The standard format for an identification number shall be “[abbreviated name of person filing]-LR-[docket identification]-[optional: NP][sequential number by person filing].” For example, “PRC-LR-CP2010-1-NP8” read right to left would be the eighth (8) non-public (NP) item filed in Docket No. (CP2010-1) as a library reference (LR) by the Postal Regulatory Commission (PRC). Alternative formats may be used when required for clear identification of the material being filed.
(d) Filing procedure. Participants filing material as a library reference shall file contemporaneous written notice of this action. The notice shall:
1. (1) Set forth the reason(s) why the material is being designated as a library reference;
2. (2) Identify the category into which the material falls and describe in detail what the material consists of or represents, noting matters such as the presence of survey results;
3. (3) Explain in detail how the material relates to the participant's case or to issues in the proceeding;
4. (4) Identify authors or others materially contributing to substantive aspects of the preparation or development of the library reference;
5. (5) Identify the documents (such as testimony, exhibits, and an interrogatory) or request to which the library reference relates, to the extent practicable;
6. (6) Identify other library references or testimony relied upon or referred to in the designated material, to the extent practicable;
7. (7) Indicate whether the library reference is an update or revision to another library reference and, if it is, clearly identify the predecessor material; and
8. (8) To the extent feasible, for proceedings scheduled for a hearing on the record, identify portions expected to be entered into the record and the expected sponsor (if the participant filing a library reference anticipates seeking, on its own behalf, to enter all or part of the material contained therein into the evidentiary record). To the extent feasible, in all other proceeding types, identify portions relevant to the proceeding.
(e) Optional preface or summary. Inclusion of a preface or summary in a library reference addressing the matters set out in paragraphs (d)(1) through (8) of this section is encouraged, but optional.