Microsoft Outlook PST 2003 (Unicode)

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Microsoft Outlook PST 2003 (Unicode)

Table of Contents

Identification and description
Local use
Sustainability factors
Quality and functionality factors
File type signifiers
Notes
Format specifications
Useful references

Format Description Properties

ID: fdd000378
Short name: PST_Unicode
Content categories: text, email
Format Category: file-format
Other facets: unitary, binary, structured, symbolic
Last significant FDD update: 2025-04-09
Draft status: Full

Identification and description

Relationship to other formats
Full name	Microsoft Outlook 2003 Personal Folders File (Unicode)
Description	The Personal Folders File or PST is an open proprietary data file format used to store local copies of messages, calendar events, and other items within Microsoft software including Microsoft Office Outlook. PST files are used to store archived items and to maintain off-line availability of the items. See PST_ANSI for a description of general PST structure and characteristics. The two versions of PST, PST_ANSI and PST_Unicode, are differentiated primarily by software implementation versions, character sets, maximum file size constraints and bit values. PST_Unicode is the default format used by Office Outlook versions starting with Outlook 2003 and includes Outlook 2007, Outlook 2010 and Outlook 2013. It employs the Unicode character set. The file size constraints for PST_Unicode are significantly larger than the PST_ANSI overall size limit of 2 gigabytes (GB). PST_Unicode can support file sizes up to 20 GB in Outlook 2003 and Outlook 2007 and file sizes up to 50 GB for Outlook 2010, Outlook 2013, Outlook 2016. According to Microsoft, these file size limits can be extended but would negatively impact performance. PST_Unicode uses 64-bit values to represent block IDs (BIDs) and byte index (IB).
Production phase	PST files provide a mechanism for the centralized storage of email folders, email messages, their attachments, contacts, calendar items, etc.
Has earlier version	PST_ANSI, Microsoft Outlook PST 97-2002 (ANSI)
Affinity to	TNEF, Transport Neutral Encapsulation Format

Local use

LC experience or existing holdings	The Library of Congress includes PST Unicode and PST ANSI files in its collections, especially in the Manuscripts and Music Divisions as well as other personal papers repositories.
LC preference	The Library of Congress Recommended Formats Statement (RFS) lists PST as an acceptable format for Email. The RFS does not specify a version of PST.

Sustainability factors

Disclosure