A presentation by Geof Huth on the PDF/A preservation format presented at a meeting of the Mid-Atlantic Regional Archives Conference in Bethlehem, Pennsylvania, on October 21, 2011. This presentation puts PDF/A in the context of a digital preservation program and explains the uses of its format and some of the details of this international standard.

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PDF/A
A Preservation Format
Mid-Atlantic Regional Archives Conference
21 October 2011
Geof Huth
geofhuth@gmail.com

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File Format Confusion
 From 5,000 to 15,000 extant file formats
 Most are proprietary
 The numbers add complexity to preservation
 Real preservation formats are few in number
 And we can really count on none of them

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Two General Classes of Formats
 Proprietary
 Controlled by one company
 Underlying code is a trade secret
 If the company goes under, the file format becomes obsolete
 Open
 Controlled by a standards body, a consortium, wiki-like bodies
 Code is free and open to all
 In absence of an “owner,” can still use the code to make a reader
 Neither Guarantees Preservation
 But open formats give you an opening to preservation

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Proprietary Formats
 Tend to be rich in features
 Limited readers for each format
 Limited ability to exchange data
 Difficult for long-term accessibility
 Greater associated costs

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Advantages of Open Formats
 More choice in what application to use
 Better exchange of data
 Better support of long-term preservation
 Possible lower costs
 Ability to create own readers

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Format/Software Confusion
 Software
 Creates a file in the format
 Reads the file for you
 Allows you to interact with the file
 Format
 Is the specific technical form in which a certain file exists
 Can be created by one software product or many
 Examples
 Adobe Acrobat (and many others) vs PDF
 Microsoft Word vs .doc (and .docx, etc.)

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Criteria for Preservation Formats
(and Files)
 Ubiquitous
 Long-lived
 Documented
 Metadata-supporting
 Accurate
 Open
 Uncompressed
 Unencrypted

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When to Use a Preservation Format
 Creation
 Begin with a format you know will last
 If so, choose a format that allows modification to a file
 Recordation
 When information becomes a record, save it in a chosen format
 This freezes the file and demonstrates it is a record
 Archiving
 Convert to persistent formats those records needed long-term
 The conversion preserves the records and marks is as permanent
 Early Action Can Save Money and Time

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Normalization
(action at the point of archiving)
 Conversion to a format
 Not expected to change
 Not expected to disappear
 Not expected to become unreadable
 Usually conversion to a different format from original
 Generally how preservation formats are used
 Still, may cause data loss or corruption

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Options for Preservation of Text
 American Standard Coding for Information Interchange (ASCII)
 Unicode
 Portable Document Format / Archive (PDF/A)
 Extensible Markup Language (XML)
 Open Document Format (ODF) (ISO/IEC 26300:2006)
 Office Open XML (OOXML) (ISO/IEC 29500:2008)

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What is Portable Document
Format?
 Originally developed by Adobe in 1991
 Specifications made available for free in 2001
 Format made an open international standard in 2008
 Includes text and image features

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Advantages of PDF
 Has accessibility across platforms
 Saves look and searchability of original
 Embeds fonts (if desired)
 Allows copying of text from files
 Remains fairly stable and universal
 Is difficult to modify
 Has enhanced document security
 Supports authenticity

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Disadvantages of PDF
 Won’t always perfectly represent original
 Some files are more difficult to convert
 Some formatting may be lost if saved back to original file format
 Limited ability to modify
 A complex format saving image and text
 Tends to be larger than a word processing document

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PDF’s Advantage over Others
 Image and text in one bundle
 Intelligent text
 Accepts importance of format to meaning
 Ubiquity of format and readers

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Conversion Practices
 Have necessary fonts installed
 Ensure lossless compression
 Important for embedded images
 When converting PDF to PDF/A
 Eliminate prohibited features
 Check beforehand or fix during

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Flavors of the PDF Standard
 PDF (vanilla)
 PDF/A (for archival preservation)
 PDF/X (for publishing)
 PDF/E (for engineering drawings)
 PDF/VT (for variable data and transactional printing)
 PDF/UA (for accessibility—in development)
 PDF/H (for healthcare records—a guide, not a standard)
 GeoPDF (for geospatial records—only based on standards)

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Portable Document Format /
Archive Standards
 PDF/ A-1
 ISO Standard 19005-1:2005
 Based on PDF Reference 1.4 (Acrobat 5)
 PDF/A-2
 ISO Standard 19005-2:2011
 Based on PDF Reference 1.7
 Published 20 June 2011
 New versions of PDF/A expected

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Uses of PDF/A
 Standard textual documents
 Paper documents
 Word-processing and PDF documents
 Sequences of related digital images
 Documents where appearance matters
 Static documents

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Less Appropriate for PDF/A
 Webpages
 Databases
 Spreadsheets
 Dynamic documents

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Creating PDF/As
 Need a product that can produce one
 Like Adobe Acrobat 8 Professional
 Can convert documents individually
 Opening and converting one at a time
 Can use batch processing
 Converting multiple documents at once
 Supported by Acrobat 8

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General Goals of PDF/A
 Specifies limited stable set of features
 To ensure long-term validity
 Eliminate features that are not “archival”
 An open preservation standard
 Format designed to be a preservation standard

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Required in PDF/A
 All fonts embedded
 Unlimited legal use of embedded fonts
 Device-independent color
 Metadata describing the file
 File must self-identify the PDF/A version

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Excluded from PDF/A-1
 Audio and video content
 JavaScript and executable files
 Encryption
 LZW and JPEG 2000 image compression
 Reference to outside content
 Transparency
 Embedded files

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Differences in PDF/A-2
 Allows embedding of OpenType fonts
 Allows JPEG2000 image compression
 Supports transparent objects
 Supports layers, which can be hidden for viewing
 Defines use of digital signatures
 Defines rules via PDF Advanced Electronic Signatures (PAdES)
 Specifies requirements for custom XMP metadata
 Allows embedded files, but in only one context
 In a PDF/A-2 you can embed PDF/A files
 Allows creation of sets of documents in a single file (e.g. emails)
 All PDF/A-1s are compliant with PDF/A-2 standard
 PDF/A-2 is an extension of PDF/A-1

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PDF/A-1 Conformance Levels
 PDF/A-1, Level A (full compliance)
 Preserves document’s logical structure
 Preserves text stream in reading order
 Requires language specification
 Requires UNICODE mapping
 PDF/A-1, Level B (minimal compliance)
 Preserves visual appearance
 Doesn’t require as much descriptive info
 Less “accessible” format

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Flavors of PDF/A
 PDF/A-1a (a = accessible)
 RGB Color
 CMYK Color
 PDF/A-1b (b = basic)
 Same color choices
 PDF/A-2a (extension of A-1a)
 PDF/A-2b (extension of A-1b)
 PDF/A-2u (u = Unicode)
 Must use Unicode
 Does not require representation of logical structure

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PDF/A Product Lines
 Adobe Acrobat (www.adobe.com)
 Apago (www.apagoinc.com)
 Callas (www.callassoftware.com)
 Compart (www.compart.net)
 PDFlib (www.pdflib.com)
 PDF Tools AG (www.pdf-tools.com)

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PDF/A Validation Tools
 Adobe Acrobat Preflight Function (www.adobe.com)
 Callas Software pdfaPilot (www.callassoftware.com)
 PDF Tools AG's 3-Heights PDF Validator (www.pdf-tools.com)

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Formats are Not Everything
 Preservation Programs Require Work
 Conversion procedures
 Quality control
 Version control
 Environmental controls
 Metadata creation and maintenance
 Metadata about the records and their information
 Metadata about your preservation actions
 Data management controls (backups, etc.)
 Ensuring that chosen normalized formats are still valid
 Vigilance