This document provides guidance to participating organizations around file naming practices when submitting digital materials to the Minnesota Digital Library (MDL). File names that do not follow these guidelines add additional risk to digital preservation and create unnecessary access issues. Files not following these guidelines may need to be renamed. If you have questions, please contact MDL Outreach Coordinator Molly Huber at mollyh@umn.edu or 612-301-1329.
1. Avoid using special characters or emojis in file names
Computers and other electronic devices frequently use the characters listed below for specific tasks in an electronic environment. For example, a forward slash is used to identify folder levels in Microsoft products, while Mac operating systems use the colon. Periods are used in front of filename extensions to denote file formats such as .jpg and .doc; using them in a file name could result in lost files or errors. Using these reserved characters can cause the system to misinterpret or be unable to read the file. The special character list below is not exhaustive.
Do not use special characters or emojis such as: \ / : ? “ . @ < > | [ ] % $ & * 😀👍
However, characters such as _ and - ARE acceptable.
2. Use underscores or CamelCase instead of periods or spaces
As stated above, periods have a specific function in a file name (indicating where the file extension begins). Spaces are often translated in a web environment as “%20”. If viewed online a file name would change from John Smith Portrait.jpg to John%20Smith%20Portrait.jpg. This may cause confusion in identifying the actual file name. Spaces and extra periods also cause issues with tools used for file preservation.
Instead of using John Smith Portrait.jpg
Use something like this: John_Smith_Portrait.jpg or JohnSmithPortrait.jpg.
If a date is included in a file name use something like: JohnSmithPortrait_1924-01-11.jpg or 1924-01-11_JohnSmithPortrait.jpg.
If you want to use numbers to indicate the order of multiple related files use something like: JohnSmith_001.jpg, JohnSmith_002.jpg, etc.
3. Limit the length of the file name
Different operating systems and software have different limits on the acceptable length of file names and file paths. Some systems allow up to 256 characters, while others allow far fewer. Keeping file names short can help prevent any future issues. Generally about 25-30 characters is a sufficient length to capture enough information for naming a digital file. Please note that the number of characters in a file name may include the names of the folders the file is stored in. Keep this in mind if the files are nested in multiple folders.
4. File names should be unique
When adding files to an online repository such as MDL, file names often become an additional “identifier”. As such, these identifiers should be unique to avoid confusion. For example, an MDL Identifier number is UMN002315.tif and UMN002316.tif and so on in order to ensure uniqueness across all files submitted. If your item has multiple pages/parts, it is suggested to use numbering to indicate the page order such as UMN007477_001.tif, UMN007477_002.tif, UMN007477_003.tif, UMN007477_004.tif, etc. Make sure you use enough leading zeros based on the number of pages/scans you have so items sort properly.
5. File names might be descriptive
Files are frequently copied to other folders, downloaded, and emailed. They may be migrated to newer storage, or moved permanently if transferred to the archive. It is important to ensure that the file name, independent of the folder where the original file lives, is sufficiently descriptive or unique. Instead of having multiple files named dsc0001.jpg, it will be more helpful to name the file milk_ad_dsc0001.jpg.
6. If using dates in file names, think about sorting and be consistent
If adding dates in your file name is helpful, be consistent with the location of the date. Also think about how files will sort when adding dates. Dates are often used as additional descriptive information as part of point #5 above.
Examples include: JSmithPortrait_1924-01-11.jpg or 1924-01-11_JSmithPortrait.jpg
However, if you want to sort files by a date, start the file name with the year, not the month, such as: 1984-03-24_JSmithPortrait.jpg which would sort before 1987-01-24_JSmithPortrait.jpg so they sort in chronological order. If you started the file name with the month, the January file (1987) would sort before the March file (1984).
Created by the Electronic Records Management Group (lib-ertf@umn.edu) at the University of Minnesota Libraries for the Minnesota Digital Library. Provides the minimum best practices for file naming. Adapted from Best Practices for File Naming, July 2019, Version 2.0, NC Department of Natural and Cultural Resources.