Sustainability of Digital Formats: Planning for Library of Congress Collections

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RAR Archive File Format, Version 4

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name RAR Archive File Format, Version 4
Description

Roshal ARchive format version 4 (RAR4) is sometimes also referred to as version 2.9. PRONOM fmt/411 uses the title version 2.9 but WinRAR 5.0 and RAR for Android refer to this format as RAR4. See RAR_Family for details on the file structure.

Some of the key features of RAR4 include

  • Default size of the RAR compression dictionary is 32MB
  • Encryption of both file data and file headers
  • Change in file extensions from {volume name}.rar, {volume name}.r00, {volume name}.r01, etc. to {volume name}.part001.rar, {volume name}.part002.rar, etc
  • File names and archive comments are stored in UTF-16 encoding format
  • Improved compression over previous versions because the compression dictionary is increased to 4 MB
  • Support for archive files larger than 9 GB
Production phase See RAR_Family
Relationship to other formats
    Subtype of RAR_Family, RAR Archive File Format Family
    Has earlier version RAR3, RAR Archive File Format, Version 3
    Has later version RAR5, RAR Archive File Format, Version 5

Local use Explanation of format description terms

LC experience or existing holdings See RAR_Family.
LC preference None

Sustainability factors Explanation of format description terms

Disclosure See RAR_Family
    Documentation See RAR_Family.
Adoption See RAR_Family
    Licensing and patents See RAR_Family
Transparency See RAR_Family
Self-documentation See RAR_Family
External dependencies See RAR_Family
Technical protection considerations See RAR_Family

Quality and functionality factors Explanation of format description terms

Other
Bundling/compression See RAR_Family

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension See note.  See RAR_Family
Internet Media Type See note.  See RAR_Family
File signature Hex: 52 61 72 21 1A 07 00
ASCII: Rar!
Wikipedia states that this magic number is applicable for RAR1.5 - RAR4 although Gary Kessler's File Signature Table and RAR 5.0 archive format tech note only specifically list this magic number for RAR4, not earlier versions. Acritum Software's description of RAR version 3.93 (not described at this site) lists this value for all versions since RAR1.5.
Pronom PUID fmt/411
PRONOM labels this as RAR version 2.9 but other documentation including WinRAR 5.0 and RAR for Android refer to this version as RAR4. See http://www.nationalarchives.gov.uk/PRONOM/fmt/411
Wikidata Title ID See note.  See RAR_Family.

Notes Explanation of format description terms

General See RAR_Family.
History See RAR_Family.

Format specifications Explanation of format description terms


Useful references

URLs


Last Updated: 07/11/2017