Sustainability of Digital Formats: Planning for Library of Congress Collections

Scope
Beginning with the 2024 review cycle, the Library of Congress Recommended Formats Statement (RFS) has incorporated a format's potential to support digital accessibility as an evaluation criteria for preferred and acceptable formats.

This information is reported as part of self-documentation, one of the seven sustainability factors. Each entry is prefaced with the Accessibility Features header in bold to make it easier to identify the information consistently on the page. It’s important to note that the RFS does not require these accessibility features to be enabled for a format, but our additions provide information on the capacity for the format to support these features.  

In 2024, the RFS team documented accessibility support for formats listed as preferred in the RFS, with work on formats identified as acceptable completed in 2025. For more information on these categorizations, see What do "preferred" and "acceptable" formats mean in the context of the RFS? in the RFS FAQ.

Comments welcome.

Defining digital accessibility in the context of this resource
The key questions we sought to answer about digital accessibility include:

• Does this format support digital accessibility features such as those described in the W3C Accessibility Principles? For example, 
• Text alternatives for non-text content (such as alt text)
• Captions and other alternatives for multimedia (and subtitles)
• Can text content be structured (as in XML) or tagged (as in PDF) for screen readers?
• Are dataset formats well-structured with page regions and headings identified, permitting tagged or marked up content, tables that are navigable to a screen reader and forms that can validate entries?

• In what way are accessibility features implemented in the format? Such as:
• Are there specific metadata tags to indicate accessibility features such as alt text, captions, transcripts and the like?
• Are embedded closed captions supported? Does the file rely on external data, such as WebVTT file for caption data?  

Levels of accessibility support
This resource aims to use standard language to describe accessibility support at the following levels (which may evolve over time):

• Unknown or not applicable: Use this term if there is no support identified in the specifications/resources or if unknown. Example: ESRI Arc Geodatabase (file-based) (fdd294).
• Limited: Use this term if there might be some very basic capability. Example: JFIF, JPEG File Interchange Format, Version 1.02 (fdd198).
• Moderate: Use this term if there is some support but perhaps not explicitly designed for accessibility or not actually used. Example: WAVE Audio File Format (fdd001).
• Good: Use this term if there are dedicated components in the file that support accessibility features such as embedded metadata to label content, tagged text for reading order and structure for screen readers (such as in text files) or caption/subtitle/timecode/transcription options in AV wrappers. Example: MXF Archive and Preservation Format Registered Disclosure Document (SMPTE RDD 48) (fdd543).

Summary of accessibility features in fdds
This spreadsheet provides an extracted summary of the accessibility features detailed in the Self Documentation factor. It is updated monthly to reflect new or revised content with the file names representing the date of the data pull in YYYYMMDD format. The spreadsheet is in the XLSX Transitional (Office Open XML) to facilitate automated accessibility checkers. Comments welcome on improvements to the data collection and reporting.

• fdd-xml_accessibility-20251218 (xlsx)
• fdd-xml_accessibility-20251121 (xlsx)
• No October 2025 report - government shutdown
• fdd-xml_accessibility-20250905 (xlsx)
• fdd-xml_accessibility-20250808 (xlsx)
• fdd-xml_accessibility-20250707 (xlsx)
• fdd-xml_accessibility-20250605 (xlsx)
• fdd-xml_accessibility-20250505 (xlsx)
• fdd-xml_accessibility-20250404 (xlsx)
• fdd-xml_accessibility-20250307 (xlsx)
• fdd-xml_accessibility-20250204 (xlsx)
• fdd-xml_accessibility-20250110 (xlsx)
• fdd-xml_accessibility-20241206 (xlsx)
• fdd-xml_accessibility-20241118 (xlsx)
• fdd-xml_accessibility-20240913 (xlsx)
• fdd-xml_accessibility-20240808 (xlsx)
• fdd-xml_accessibility-20240618 (xlsx)