Here is a guide explaining the meaning and significance of different metadata fields while adding or editing a catalog record. The most important fields are bolded below; these are fields which you should try harder to fill as accurately as possible. If you don't know or are unsure of what should go in a certain field, you should leave it empty.

Keep in mind the following when uploading and completing metadata:

• Most items will be missing most of these fields, even if they are well-documented (either inside the file or elsewhere online). But if you upload often, you will notice patterns and learn to predict which kinds of items will have which metadata.

• Other librarians can view and edit upload metadata, even after it has been shared publicly. Mistakes can be corrected, even if they are not noticed for a long time. (If you can't correct something yourself, you can report errors here.

After you have uploaded a file, you will be taken to a screen for entering and modifying bibliographic data. At the top of the screen is a tool which allows you to fetch bibliographic data from various sources, such as another work in the Library Genesis collection, an item for sale on a digital bookstore like Amazon, or other digital bibliographic systems like the Goodreads social reviewing website or the WorldCat digital catalog. Using this tool will often fill in a lot of data, but you should still review the information yourself if you can!

The rest of the screen is taken up by individual fields for different types of bibliographic data, explained below.

• Title. The name of the book/monograph/etc. being uploaded. If it has a subtitle (“This is the Title: And This is the Subtitle”), include that as well, to help distinguish it from other files. If the title is given in more than one language, place an = sign between versions (“Words: The Book = Palabras: El libro”).

• Volume / Part. Some books are published in volumes; for example, an encyclopedia may have a “Volume 1: A-F”, “Volume 2: G-Q”, and a “Volume 3: R-Z”. Here, you can enter this information, without the word “volume”.

• Author(s) or editor(s). Here, you enter the name of the person or entity which is credited with producing the book/monograph. Enter names as they are given in the book, separated with commas or semicolons. If there are multple authors, enter them all; if there are multiple editors, enter them all. If there are translators, enter the translators too!¹⁾

• Language. The language of the work. If the work is multilingual, enter each language (for example “English; French; Japanese”).²⁾ Try to always use English language names (you can select it from the drop-down list).

• Edition. The edition, or version, of the work. For example: books released today may be published in distinct paperback (softcover), hardcover, and ebook editions, which have some small differences. Another example: a book that was originally published 20 years ago may have been republished recently in a new edition, with new material. It is helpful to let readers know which version of something is catalogued.

• Series and volume number (if applicable). Many books are parts of series. For example, an academic publisher may have a long-running series on a certain topic, or a mass-market book (especially fiction) may be just one part of a planned multi-book series. Here, you can enter the name of the series and the number (if any) assigned to this upload. Please follow the format “series title; series volume number”, without specifying the word “volume” or anything like that (“vol.”, “v.”).

• Pages. The number of pages in the work, according to the publisher. Usually just a number, but sometimes more detailed, such as “xxxiv,228” or “xxxiv+228” (34 roman numerated pages, followed by 228 normally numbered pages). This is not necessarily the same as the number of pages actually in the file, which is automatically detected for fixed layout formats (PDF, DjVu). Often it's useful to compare the numbers - for example, to detect if a file may be missing pages, or if a scanned copy of a book is in a double-page scan layout. In a record entry, number of pages according to the publisher is noted as biblio, while the number of actual pages in the file is noted as tech.

• Year. The year the specific edition of the work being uploaded was published. For example, if you are uploading a book that was originally published in 1989, but it is a new version with updated content published in 2011, you should put 2011 in this field (as well as indicate the version in the 'Edition' field).

• Publisher. The organization which released the work. This is usually a special company dedicated to creating and selling books. Sometimes it is not a “for-profit” organization; sometimes, it's just the author. Some works are collaborations between two or more publishers.

• City. The city/town/community where the publisher has its headquarters. Some publishers have headquarters on several different continents or in several different countries; it's not necessary to list more than a couple.

• Periodical. Some works are special editions of a periodical (like an academic journal or a magazine). If so, this field is where you enter the name of the periodical.

• ISBN (ISBN-10 / ISBN-13, comma-separated). International Standard Book Number. While many commercial books and monographs from the last few decades have been assigned ISBNs, many are not (for example, some self-published or not-for-profit works). Any work with an ISBN-10 also has a corresponding ISBN-13. You should generally look for an ISBN, but they only began to spread widely around 1970 and mostly in the Western world, so before a certain point they will not be found.

Some books can have multiple ISBNs: for a hardcover/hardback/hardbound version, for a paperback/softcover version, for digital editions in different formats, etc. If possible, try to include all ISBNs that are relevant to the title, edition and, in case of a digital edition ISBN, the file format - usually they are all listed in the book itself.

For translated books, do not include the ISBN of the original edition (alas, it is a common mistake).

• ISSN. International Standard Serial Number. A unique identifier like an ISBN, but less common for books and assigned exclusively to series. For example, the first and third book in an academic publishing series on biology will almost certainly have different ISBNs, but the same ISSN.

• DOI. Digital Object Identifier. A unique identifier assigned to a work (not necessarily a book), usually scholarly. More common for academic papers than books, but academic presses frequently have DOIs assigned to electronic versions of monographs.

• Google Books ID. A unique identifier for a specific version of a work on Google Books. In the following examples, the Google Book URLs contain ID PhRZDwAAQBAJ: https://books.google.com/books?id=PhRZDwAAQBAJ https://www.google.com/books/edition/Shadow_Libraries/PhRZDwAAQBAJ

• ASIN. Amazon Standard Identification Number. A unique alphanumeric identifier assigned to works on the Amazon ecommerce platform. For books it's usually assigned if there is no ISBN. The value always begins with “B0”.

• Open Library ID. A unique alphanumeric identifier assigned to worrks on the Internet Archive's Open Library project. Begins with “OL”.

• DDC. Dewey Decimal Classification. A number assigned to works in the proprietary system originally developed in the United States by Melvil Dewey.

• LCC. Library of Congress Classification. An alphanumeric (with periods and spaces) identifier used in the system developed by the United States Library of Congress. Not to be confused with the LCCN (Library of Congress Control Number), which is only numeric.

• UDC (УДК in Russian). Universal Decimal Classification (“Универсальная десятичная классификация” in Russian). An identifier derived from a system intended for international use (as opposed to the national origins of the DDC and LCC). While widely used, it is less commonly found within mass-market works due to the influence the the Western world classification systems. Mostly used in Russia, the post-Soviet states and Latin America (in Spanish it's called CDU = Clasificación Decimal Universal).

• LBC (ББК in Russian). Library-Bibliographical Classification (Библиотечно-библиографическая классификация). Used in Russia and the post-Soviet states.

• Topic. A less-than-comprehensive classification system that nevertheless allows users to classify works from a drop-down menu within the uploader. [deprecated and going to be replaced with DDC]

• Tags. This field allows free entry of subjects or topics to classify works. Clicking a tag on an item record will display other items with the same tag. Use semicolons to separate tags.

• Cover image URL. A relative file path or an URL to the cover image. The web uploader is trying to automatically extract a cover image from the uploaded file - the first page in case of PDF or DjVu, or a corresponding cover image for most other formats. If you use the “Fetch bibliographic data” form it will replace it with a cover image from the source. You can also enter an external URL to a cover image.

• Description. A description of the work, book abstract. Most often, the publisher's promotional description is used, but the field is free entry.

• Table of contents. A listing of the different sections of the work. For any PDF and DjVu uploads with bookmarks, this is automatically generated, and then you can edit if necessary.

• Scan. Whether or not the upload has been scanned from a physical copy (rather than produced specifically as an electronic work).

• DPI. Scan resolution in dots per inch, often used to estimate the quality of a scan. The web uploader tries to automatically detect the most common page DPI for DjVu files.

• Textual / OCR. Whether or not a work has selectable text (which can then be copy-and-pasted, read by a screen reader, etc.). In scanned works, this is often created via Optical character recognition. Automatically detected for PDF and DjVu files that have a text layer.³⁾

• Paginated. Indicates whether the pages of the file contain a single logical page or a split double page.

• Page orientation. Here you can indicate whether the main orientation of a paginated work is portrait (longer or taller than it is wide) or landscape (the opposite) oriented. Some works are neither!

• Colored. Whether or not the file is a mostly 'in color', as opposed to grayscale or black and white. For predominantly text-based works, you may want to use this field to indicate whether the illustrations are in full color.

• Cleaned. Whether or not a scanned work has been “cleaned” to remove extraneous markings and other physical artifacts.

• Bookmarks. Whether or not a file has an internal bookmarking system to indicate different sections/chapters. Automatically detected for PDF and DjVu files.

• Source repository/collection. The source repository, collection or library from which the file was taken. You may want to use this field to indicate if a work is being reuploaded from another library, for example.

• Source repository/collection volume. This was relevant for some organized collections, like KOLXO3 Library, that have been imported into LibGen in the early years.

• Commentary. Any technical notes about the file features/disadvantages/differences. Useful for explaining if some chapters or pages are missing, if the layout is unusual, etc.