THE BENEFITS AND RISKS OF THE 

PDF/A-3 FILE FORMAT FOR ARCHIVAL 

INSTITUTIONS

AN NDSA REPORT

February 2014

Authors 

• Caroline Arms, Library of Congress contractor

• Don Chalfant, National Archives and Records Administration 

• Kevin DeVorsey, National Archives and Records Administration 

• Chris Dietrich, National Park Service 

• Carl Fleischhauer, Library of Congress

• Butch Lazorchak, Library of Congress

• Sheila Morrissey, ITHAKA 

• Kate Murray, Library of Congress

Representing the NDSA Standards and Practices Working Group
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CONTENTS 

EXECUTIVE SUMMARY ......................................................................................................... 2

ABOUT THE NATIONAL DIGITAL STEWARDSHIP ALLIANCE .................................................. 3

PDF/A-3 FORMAT BACKGROUND ........................................................................................ 4

PDF/A-3 STANDARDS WORKING GROUP ............................................................................. 5

PDF/A-3 ANALYSIS ............................................................................................................... 7

SPECIFIC SCENARIOS .......................................................................................................... 12

U.S. NATIONAL ARCHIVES AND RECORDS ADMINISTRATION (NARA) SCENARIOS ............ 12

LIBRARY OF CONGRESS SCENARIO..................................................................................... 15

U.S. HOUSE OFFICE OF THE LEGISLATIVE COUNSEL (HOLC) SCENARIOS............................. 17

CONCLUSIONS ................................................................................................................... 18

APPENDIX A: RESOURCES AND REFERENCES .................................................................... 21

GLOSSARY .......................................................................................................................... 23

This work is licensed under a Creative Commons Attribution 3.0 Unported License. 

Persistent URL: http://hdl.loc.gov/loc.gdc/lcpub.2013655115.1 
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EXECUTIVE SUMMARY 

As the most recent iteration of the PDF/A series of specifications, PDF/A-3 adds a single and highly significant 

feature to its predecessor PDF/A-2 (ISO 19005-2:2011). The PDF/A-2 specification permitted the embedding of 

other files as long as the embedded files were valid PDF/A files. PDF/A-3 (ISO 19005-3:2012) permits the 

embedding of files of any format (including XML, CSV, CAD, images, binary executables, etc.), within a PDF/A file. 

This new feature is intended to expand the functionality of PDF/A from “electronic paper” (albeit suitable for 

use over the very long term) to an archival format for a page-oriented document that can be bundled with 

related files. While a PDF/A file’s primary document is intended to be robust against preservation risks over the 

very long term, PDF/A-3 does not require that the embedded files be considered archival content. A PDF/A-3 

conformant reader is responsible for presenting only the primary document, but permits extraction of 

embedded files for use with other tools. 

The NDSA PDF/A-3 Working Group recognizes that there are scenarios in which such an “archival bundling” use 

of PDF/A-3 might make sense. The concept of “hybrid archiving” has been proposed, where a source document 

in a less preservation-robust format is edited and then embedded in a “save-as” PDF/A-3 file, thereby having an 

always-current version of the document in a preservation-robust format. PDF/A-3 could also be employed in 

transactional workflows, where the “classic” PDF document would contain human-readable content, and 

presumably-equivalent content in embedded files of another format (typically XML), which would be processed 

by machine. Both scenarios would require PDF/A-3 processors that have been extended with custom 

capabilities tailored to the scenario. 

For memory institutions, any such use of embedded files in PDF/A documents would depend on very specific 

protocols between depositors and archival repositories, clarifying the formats acceptable as embedded files, and 

defining a workflow that guarantees that the relationship between the PDF document and any embedded files is 

fully understood by the archival institution. Of greater concern is the possibility for PDF/A-3 to be used in some 

scenarios as a general-purpose bundling format, with the visible primary document of less long-term importance 

than the embedded files. 

Further, the scenarios presented above are complicated by the fact that their articulation is not a part of the 

standard itself. Nor do the use cases articulated by proponents of the new standard address the complexities 

implied by retaining PDF/A’s character as the digital equivalent of acid-free paper, while at the same time 

permitting its use as a general-purpose archival bundling format. In the latter case especially, the complexity of 

the PDF format and the potential and actual resulting faultiness of PDF rendering implementations and creating 

applications suggest that PDF/A-3 may be appropriate for use in controlled workflows, but may not be an 

appropriate choice as a general-purpose bundling format. 

The working group strongly recommends that tools that create PDF/A-compliant documents be engineered to 

identify (through the pdfaid:part element) files that have no embedded files, or whose embedded files are all in 

PDF/A format, as compliant with PDF/A-2 rather than PDF/A-3.

The proposed creation by the PDF Association of a free and open source PDF validation tool might mitigate the 

long-term preservation risks constituted by the complexity of the PDF/A format as a bundling format. Absent 
THE BENEFITS AND RISKS OF THE PDF/A-3 FILE FORMAT FOR ARCHIVAL INSTITUTIONS 

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such robust validation tools, conversion of PDF files to PDF/A in preservation workflows remains a somewhat 

problematic preservation tactic. 

Further, should the consensus of the preservation community be that PDF/A-3 is inappropriate as a generalpurpose archival bundling format, then the community must identify and/or create tools that make it possible to 

bundle together complex digital objects with sufficient manifest information (i.e. metadata) to establish the 

relationship amongst the components within the bundle. Such a bundling format might usefully be based on the 

BagIt File Packaging Format and/or a constrained form of the ZIP format, such as the proposed ISO/IEC 21320-1 

“Document Container File” specification (as of December 2013, this standard is still under development). 

ISO/IEC 21320-1 is intended to be a formally-specified interoperable and royalty-free subset of the proprietary 

ZIP format developed and maintained by PKWARE. BagIt is a hierarchical file packaging format for storage and 

transfer of arbitrary digital content. A typical serialization as a single file is based on ZIP or TAR. Operational 

elements of archival strategies often include (a) a list of preferred and acceptable formats with associated levels 

of commitment or confidence with respect to long-term preservation and access and (b) action plans for each 

format that govern procedures on ingest. Many institutions have given PDF/A a high priority on such lists and 

assumed that files that comply with the PDF/A-1 and PDF/A-2 standards require no normalization on ingest. 

PDF/A-3 must be treated separately from the other PDF/A versions in preference lists and for action plans and 

with more caution. 

The introduction of such a problematic new feature in the latest version of the PDF/A family suggests that 

perhaps the community of memory institutions need to take a more strategic, active, and vocal role in the 

standards development process. 

ABOUT THE NATIONAL DIGITAL STEWARDSHIP ALLIANCE 

Founded in 2010, the National Digital Stewardship Alliance (NDSA) is a consortium of institutions that are 

committed to the long-term preservation of digital information. NDSA’s mission is to establish, maintain, and 

advance the capacity to preserve our nation’s digital resources for the benefit of present and future generations. 

NDSA member institutions represent all sectors, and include universities, consortia, professional associations, 

commercial enterprises, and government agencies at the federal, state, and local levels. 

More information about the NDSA is available from http://www.digitalpreservation.gov/ndsa/. 
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PDF/A-3 FORMAT BACKGROUND 

In general, PDF/A-3 is a constrained form of ISO 32000-1,1 also known as Adobe PDF 1.7.2 PDF/A-3 is intended to 

be suitable for archiving page-oriented documents for which PDF is already being used in practice. 

The specification, which goes by the full name of Document management — Electronic document file format for 

long-term preservation — Part 3: Use of ISO 32000-1 with support for embedded files (PDF/A-3) (or ISO 19005-

3:2012 for short),3 defines a file format based on PDF which provides a mechanism for representing electronic 

documents in a manner that preserves their static visual appearance over time, independent of the tools and 

systems used for creating, storing or rendering the files. The preservation of the “static visual appearance” is 

only possible if conforming PDF/A files are complete in themselves and require no external resources (for 

example, unembedded fonts) for them to render their pages properly. 

PDF/A-3 adds a single and highly significant feature to its predecessor PDF/A-2 (ISO 19005-2). PDF/A-3 permits 

the embedding within a PDF/A of files in arbitrary formats (including XML, CSV, CAD, images, binary executables, 

etc.), not just other PDF/A files (as previously permitted in PDF/A-24

).

While allowing the embedding of files of any type, PDF/A-3 imposes requirements and adds capabilities that do 

not apply to ISO 32000-1 documents as a whole. For example, an explicit association must be made between 

each embedded file and the containing PDF or object or structure (e.g., image, page, or logical section) within 

the PDF/A-3 file. Embedded files that comply with PDF/A-3’s requirements are termed "associated" files. Each 

associated file is required to include an “AFRelationship” key that must contain a value that represents the 

relationship of the embedded object to the “primary document” in the PDF/A-3 file. 

The values for the AFRelationship keys defined in the PDF/A-3 specification are Source, Data, 

Alternative, Supplement, and Unspecified. Additionally, PDF/A-3 requires that MIME types be 

provided for associated files; the application/octet-stream MIME type is required if a more specific MIME type 

for the embedded file is not available. While explicit associations are made, the semantics of the associations 

may be too coarse-grained for some archival institutions. Human-readable descriptions for the associated files 

can be provided and are recommended. 

 

1 ISO 32000-1:2008 Document management -- Portable document format -- Part 1: PDF 1.7 Available at 

http://www.iso.org/iso/catalogue_detail?csnumber=51502 

2 Adobe Systems Incorporated. Document Management – Portable Document Format – Part 1: PDF 1.7, First Edition. Jul 2008. 

Available at 

http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/PDF32000_2008.pdf 

3 ISO 19005-3:2012 Document management -- Electronic document file format for long-term preservation -- Part 3: Use of 

ISO 32000-1 with support for embedded files (PDF/A-3). Available at 

http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=57229 

4 ISO 19005-2:2011 Document management -- Electronic document file format for long-term preservation -- Part 2: Use of 

ISO 32000-1 (PDF/A-2). Available at 

http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=50655 
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The PDF/A-3 specification recommends that a conforming reader not render any non-PDF/A-3-conformant file 

embedded in a PDF/A-3 file, but does not forbid such rendition. The specification also recommends, but does 

not require, that a conforming reader enable the extraction of any embedded file, and, in addition, recommends 

but does not require that such an extraction be initiated by an explicit user action. Extraction is defined as 

"copying the raw byte stream of the embedded file data (after any decoding of filters that might be applied) 

from inside the PDF to some external byte storage system (e.g. disk or memory).” The standard notes that 

"these recommendations are to aid users in avoiding potential security risks inherent in opening unknown file 

types." 

The changes introduced by the PDF/A-3 specification introduce both benefits and risks that archival institutions 

must consider. These issues are detailed in the “PDF/A-3 Analysis” section below. 

PDF/A-3 STANDARDS WORKING GROUP 

The PDF/A-3 Working Group was given a charter to investigate the PDF/A-3 standard by the NDSA Standards and 

Practices Working Group at its December 17, 2012 meeting. 

In its charter, the NDSA PDF/A-3 Working Group stated that its members would research the pros and cons of 

using the PDF/A-3 standard in different preservation scenarios, including use as an extension to PDF/A-15

 and 

PDF/A-2 in circumstances for which those formats have been adopted or recommended, and use as a wrapping 

or bundling format for various digital asset/media types, such as textual, audio, video, photo and GIS data. 

The goal of the Working Group is to develop guidelines for the appropriate use of PDF/A-3 with respect to 

different scenarios, including both detailed technical information and a practical quick reference guide for endusers. In particular, the Working Group has worked to determine whether or not PDF/A-3 is appropriate as a de 

facto wrapping or bundling format for some or all media types or in particular circumstances, and, for 

circumstances in which PDF/A-2 has already been deemed an appropriate preservation format (primarily for 

textual documents), identify and explore the risks and opportunities are offered by the ability to embed nonPDF/A content in PDF files. 

Working Group Members 

The following are the members of the PDF/A-3 Standards Working Group: 

 Caroline Arms, Library of Congress contractor 

 Don Chalfant, National Archives and Records Administration 

 Kevin DeVorsey, National Archives and Records Administration 

 Chris Dietrich, National Park Service 

 Carl Fleischhauer, Library of Congress 

 Butch Lazorchak, Library of Congress 

 Sheila Morrissey, ITHAKA 

 

5 ISO 19005-1:2005 Document management -- Electronic document file format for long-term preservation -- Part 1: Use of 

PDF 1.4 (PDF/A-1) Available at 

http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=38920 
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 Kate Murray, Library of Congress 

Outreach 

In addition to, and as part of, the Working Group’s monthly phone meetings, the Working Group sought 

information from others engaged in the PDF/A-3 community. This outreach included: 

 Attending the Digital Preservation Coalition (DPC) Workshop on PDF/A-3 in Leeds, UK, in March 2013.6 

This workshop included presentations by members of the PDF Association and the PDF/A Competence 

Centre. Many of the members of both of these organizations are engaged in producing commercial 

tools for the use of PDF/A-3. In addition, there were presentations, questions, and discussions by 

representatives of UK, US, and European memory institutions. 

 A presentation on PDF/A-3 to the working group members at a monthly phone meeting by Stephen 

Levenson, an IT Specialist for Policy and Planning at the Office of the US Courts and the chair of the 

PDF/A working group. Mr. Levenson discussed both industry and government workflows (in Germany, 

USA, and Brazil) that looked to PDF/A-3 as a means of packaging together a “human-readable” 

document with a “source file” of some type, typically XML, that contained the same intellectual content, 

and that was intended for automated processing. 

 A presentation on PDF/A-3 to the working group members at a monthly phone meeting by Duff Johnson, 

International Project Co-Leader for ISO 32000 (PDF), US Committee Chair for ISO 14289 (PDF/UA) since 

2005, AIIM's Standards Committee Chair, a member of AIIM's Board of Directors, and Vice Chairman of 

the PDF Association. 7 In the course of that presentation, Mr. Johnson spoke of an effort to have the PDF 

Association commit resources to developing a free and open-source (F/OSS) PDF validator. 

 A presentation by the NDSA PDA/A-3 working group at the PDF Association Technical Conference North 

America 2013 PDA/A day in Seattle in August 2013. This presentation, at the invitation of Duff Johnson 

after his presentation mentioned above, discussed the working group’s understanding of the PDF/A-3 

specification, its intended benefits, and its possible perceived risks. It was an occasion both to express 

the working group’s understanding of, and concerns about, the PDF/A-3 specification, and to listen to 

members of the larger PDF community, including makers of PDF/A-3 tools. One of the observations 

distilled from the conversations was the very great need for PDF/A-3 advocates and toolmakers to 

educate users about the limitations and risks of the new feature of PDF/A-3, as understood from a longterm preservation perspective. It was suggested that it would perhaps be more appropriate to speak of 

the PDF/A family as “reliable” rather than “archival” formats.

 

6 Digital Preservation Coalition, "Digital Preservation with Portable Documents: a workshop to introduce and discuss the PDF/A 

version." http://www.dpconline.org/events/details/55-DPC_PDFA3_briefing?xref=58 

7 PDF Association http://www.pdfa.org/pdf-association/ 
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PDF/A-3 ANALYSIS 

The Working Group has looked both at general pros and cons of PDF/A-3 and at scenarios where it might or 

might not be appropriate. This section discusses possibilities and risks associated with PDF/A-3 in general terms. 

The following section introduces more specific scenarios. 

Pros/Possibilities 

The Working Group recognizes that there are scenarios where the use of PDF/A-3 might make sense. Several of 

these scenarios are not archival in nature, but build on the benefit recognized in PDF/A as a constrained form of 

PDF intended to guarantee a reliable visual presentation of a page-based document. This benefit applies not 

only over time but also across computing environments. 

One scenario is "hybrid archiving." In this widely applicable scenario, a document originates and is edited by a 

word-processor, but is managed in a document management system as a PDF/A-3 file, with the source wordprocessor file embedded within the PDF/A-3 document file. In this scenario, the document is considered 

archive-ready throughout its lifecycle. However, the embedded source file is considered as a non-archival 

artifact. 

Another scenario where use of PDF/A-3 seems appropriate is one in which a document is essentially a record of 

a transaction between stages in a controlled workflow, in which the transaction record’s format requires a 

consistent visual representation across devices and operating systems (a primary objective of PDF/A), but also 

requires or benefits from a machine-processable representation of part or all of the content or metadata. This 

machine-processable representation could be in XML and employ a standard or well-known schema. The 

Working Group learned of several examples where such use of PDF/A-3 is in use or active development. 

Examples with embedded machine-readable data structures include: the ZugFERD initiative8

 for exchange of 

invoices in Germany; the use of PDF/A-3 in US Bankruptcy Court exchanges with major creditors to reduce the 

need for manual data entry in records management systems; and in the legislative process of the Brazilian 

Senate. 

Another use of embedded files in PDFs that the group learned about involved PDF as a wrapper for the audio 

from a court proceeding. The visible "primary document" provides context and metadata for the embedded 

sound file, intended for retention only for a specified period after the proceeding. 

Possible uses or benefits of PDF/A-3 that might be relevant to archival institutions include: 

 Associating machine-processable data extracts with particular charts or diagrams in a document. 

 Embedding rich metadata in a "native" or standard format that has no RDF/XMP equivalent. This 

metadata would not be subject to changes by PDF processing tools that expect to update XMP 

metadata. 

 

8 German ZUGFeRD Format for electronic Invoices. http://www.pdflib.com/knowledge-base/pdfa/zugferd-invoices/ 
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 Making explicit the function or relation of embedded files within PDF documents (i.e., non-PDF/A files). 

Files (or chunks of non-visible data) can already be embedded in PDF files in ways that are obscured 

from all but vendor-specific or application-specific reader/viewers (although not in PDF/A-1 or PDF/A-2 

files). The requirement for file specification dictionaries with required relationship values in those 

dictionaries will make associated files embedded in a PDF/A-3 more obvious and discoverable through 

generic PDF/A-3 viewers. Ingestion into a preservation system could extract all associated files (and 

MIME types) and submit them to identification/characterization/validation procedures. (NOTE: the fileassociation feature is included in the draft ISO 32000 Part 2 specification and will be available to nonarchival profiles of PDF once ISO 32000-2 is published.) 

Cons/Risks 

The PDF/A-3 specification allows an unlimited variety of files to be embedded in a PDF/A-3 document. Although 

the specification stipulates that a MIME type must be provided, MIME types do not necessarily provide the 

granular information necessary for proper file management. For example, the MIME type of 

application/octet-stream, by itself, is nearly useless. The PDF/A-3 specification does provide a 

required mechanism, the AFRelationship key, for expressing a relationship between the embedded file and the 

primary document, but the specification suggests no methods of verifying the stated relationship, nor is there 

any means in principle of doing so. 

Even with the AFRelationship key mechanism, the embedding of files in any format creates concerns for 

memory institutions receiving such content. The PDF/A-3 specification makes it clear that the primary 

document is constrained by rules that will preserve its static visual appearance over time, but makes no 

requirements for long-term usability for embedded files. This might not be sufficient to free institutions from 

other custodial responsibilities in relation to the embedded files. 

Many institutions are responsible for reviewing content for classification, copyright, or privacy concerns prior to 

public release and presumably these responsibilities would extend to attachments, in effect forcing them to 

maintain access to files in formats that they never intended to preserve. Similarly, archival institutions will have 

to take steps to assure that embedded files are not infected with computer viruses. In comparison with PDF/A-2 

(which allows embedded files, as long as they are compliant PDF/A-1 or A-2 files), PDF/A-3 suggests long-term 

preservation challenges for cultural heritage institutions that may only fully be addressed through the 

development of detailed technical acquisition policies and/or prior agreements between the depositor and the 

archival repository. Such an agreement must clarify the formats acceptable as embedded files and how the 

depositor's workflow guarantees that the relationships between the primary PDF document and any embedded 

files is fully understood by the archival institution, so that appropriate rules are applied on ingest. The 

agreement might be based on a community best practice or a formal, legal regulation. 

The primary focus of the PDF/A family of specifications, to this point, has been to define a format that supports 

the preservation of the content of page-based electronic documents. As the ISO 19005-3 specification states: 

The primary purpose of ISO 19005 is to define a file format based on PDF, known as PDF/A, which 

provides a mechanism for representing electronic documents in a manner that preserves their static 

visual appearance over time, independent of the tools and systems used for creating, storing or 
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rendering the files. A secondary purpose of ISO 19005 is to define a framework for representing the 

logical structure and other semantic information of electronic documents within conforming files. 

Another purpose of ISO 19005 is to provide a framework for recording the context and history of 

electronic documents in metadata within conforming files. 

These goals are accomplished by identifying the set of PDF components that can be used, and 

restrictions on the form of their use, within conforming PDF/A files. 

By enabling the embedding of arbitrary files within a PDF/A-3 file, the PDF/A-3 specification burdens the PDF/A 

family with an additional requirement: that of a packaging or bundling format. This additional requirement adds 

significant qualifications to the warranties implicit in terming the PDF/A family of formats as “archival.”

The support for embedded files in PDF/A-3 threatens a significant principle that informed the development of 

PDF/A-1 and PDF/A-2: that the PDF/A document instance contain within itself everything necessary (given a 

conforming reader) to extract the complete semantic value of the document. 

The PDF/A-3 specification itself neither addresses use-cases for embedding non-PDF/A files within a PDF/A-3 file 

instance, nor motivates the addition of this capability. Use cases offered by proponents of the new specification 

attempt the delicate balance of retaining PDF/A’s character as the electronic equivalent of acid-free paper while 

suggesting that the format provide a means for bundling files related to the primary document – a function that 

might well constitute a contradiction of the first purpose even as it supports real-world use-cases. 

These proponents make a distinction not made in the specification itself between “archival content” and “nonarchival content” in the PDF/A-3 file. This distinction is drawn in a use case termed “hybrid archiving.” The 

“archival content” is the constrained, reliable “digital paper” of PDF/A-1 and PDF/A-2, with all the warranties of 

those versions of the PDF/A specification. Embedded source files, permitted in PDF/A-3, comprise “nonarchival” content, which no one is to consider having any archival warrant whatsoever. In this scenario, the 

embedded files are like “junk DNA” – artifacts that travelled along with the PDF/A-3 document in the process of 

its creation, and are present merely as artifacts of its process of production, but which have no standing of their 

own, nor any necessary semantic significance. The specification, indeed, declares that embedded files “should 

not be rendered by a conforming reader” (although, if an explicit user action initiates the process, it should 

enable the extraction of the byte stream comprising the embedded file). From the perspective of memory 

institutions, it’s not clear in this scenario why these “non-archival” artifacts should continue as parts of the 

PDF/A-3 file, or, if they do continue, why a conforming reader should supply the capability to display information 

about them, or include the ability to extract their constituent byte streams. 

The hybrid archiving use case is in contrast to a different use case being actively implemented in Germany. This 

is the “document communication” use case, where PDF/A-3 is employed for electronic invoicing. The “primary 

document” component of the PDF/A-3 file presents a “human-readable” form of an invoice. The embedded XML 

file is a version of the invoice intended for machine-processing. This pair of bytestreams is intended to 

complement each other in a workflow, with the Associated File (AF) dictionary specifying the relationship 

between these two “versions” of the document as “Data.” 
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The difficulty, of course, is that there is no warrant, short of individual viewing of both the document and the 

embedded XML (which would of course involve an application in addition to a PDF viewer), that both “versions” 

of the invoice represent the same information. Given the assumed bulk machine processing of such documents, 

archival institutions may be obligated to understand the nature of the semantic content of embedded files and 

their relationship to the primary document in more complex ways than are indicated in the PDF/A-3 file in order 

to fulfill their mission. The availability and development of tools and services to assist archival institutions in 

understanding the semantic relationships amongst bytestreams in PDF/A-3 documents will assist them in 

making decisions on whether embedded files should be stripped out because they are not considered the official 

archival record and not guaranteed to be equivalent to the primary document or whether they can be retained. 

As the example of wrapping audio of a court proceeding in a contextual document illustrates, the PDF/A-3 

specification can be followed even when the primary content is an embedded file and the visible document 

merely a cover note rather than a transcript. An advantage, for the producer of such a PDF document, may be 

the ability to manage audio files within an existing document management system that is not designed to 

handle and deliver audio. Archival institutions will need to understand when PDF/A-3 might have been used in 

this way for files they receive. 

The complexity and technical transparency challenges of the PDF format for the non-expert motivated the 

restrictions placed on PDF/A instance features. Transparency is used here as defined as a sustainability factor9

by the Library of Congress in analyses of digital formats in their resource on Sustainability of Digital Formats. 

The technical transparency challenges and the complexity of the format itself (both potential and actual 

resulting faultiness of implementation in PDF writers and readers), and the absence of a reference 

implementation of any of the PDF format profiles, suggest that PDF may be inappropriate for use as a generalpurpose bundling format or submission information package. 

PDFs have proven useful for a variety of purposes, but they are not purpose-built as a bundling format. In this 

regard, the PDF is like a Swiss army knife, with the format continually expanding to meet new user needs. It is 

illuminating to compare this design approach with the UNIX philosophy of writing programs that do one thing, 

and do it well. This is not to suggest that either design approach has exclusive merit, only to suggest that for the 

long-term archival community, a purpose-built bundling format may be more appropriate. 

Because of the potential complications for the long-term preservation of PDF/A-3 files, the working group 

strongly recommends that tools that create PDF/A-compliant documents be engineered to identify (through the 

pdfaid:part element) files that have no embedded files, or whose embedded files are all in PDF/A format, as 

compliant with PDF/A-2 rather than PDF/A-3.

There is currently no robust vendor-independent mechanism for assessing that a PDF/A file does in fact comply 

fully with the standard and the conformance level it claims in its internal metadata. Experience has shown that 

attempts to create a PDF/A can easily result in an invalid file. The file produced may identify itself to be a PDF/A 

although an error message indicates a problem with its generation. Because the Adobe Reader is very forgiving, 

 

9Caroline R. Arms and Carl Fleischhauer. “Sustainability of Digital Formats: Planning for Library of Congress Collections”. 

http://www.digitalpreservation.gov/formats/sustain/sustain.shtml#transparency 
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the document may look fine to its creator. However, other PDF processors may reject it because it is technically 

invalid. 

SCENARIOS FOR PDF/A-3 USE 

The Working Group has reached the conclusion that whether PDF/A-3 is an appropriate format for the long-term 

preservation of content depends heavily on the type of content, the nature of the workflow that created it, and 

whether the archival submission process allows for detailed negotiation on allowable formats for embedded 

files. Several scenarios have been developed to present risks and benefits in particular situations. In many 

cases, these scenarios are hypothetical but they have been chosen as representative of real-world examples 

based on institutional experience. A general scenario is first, followed by some scenarios that are specific to 

particular contexts or institutions. 

General Scenario 

Scenario for embedding supporting data in PDFs for scholarly documents. 

Background and Assumptions: 

Many scholarly journals are now expecting authors to supply supporting machine-readable data extracts used as 

the basis for charts and summary tables in articles. Publishers differ as to data formats accepted and as to how 

they support access for users to the data. One common form for distributing scholarly articles is as PDF 

documents. An assumption behind this scenario is that a journal publishing system supporting the generation of 

compliant PDF/A documents is adapted to support generation of PDF/A-3 documents with data extracts 

embedded and linked to the appropriate tables and graphics. 

Scenario: 

The publisher of a scholarly journal that already uses PDF/A as one of the formats disseminated to users, 

extends its peer review, editorial, and production workflows to support generation of PDF/A-3 files for articles 

that have supporting data. 

Desirable outcomes and benefits: 

A peer reviewer using a compliant reader to consult the PDF/A-3 version of an article can easily extract the data 

extract that supports a table (or chart) of interest and evaluate whether the data does indeed support the table 

as presented. The reviewer can also evaluate whether the data extract is consistent with the journal's policies. 

A scholar using a compliant reader to consult the PDF/A-3 version of an article can easily extract the data extract 

that supports a table (or chart) of interest and perform his own analysis on the data. 

A publisher may be able to simplify its content management system by storing supporting data for an article 

within the article document. 
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Risks and disadvantages: 

A specific concern applies to numeric or tabular data. Numeric or other tabular data cannot be used effectively 

by anyone other than the authors without adequate description of the data collection context, the coding 

system employed, the accuracy of measurements, etc. As with any other bundling format, embedding a data 

extract to support a chart in a PDF should not be seen as a substitute for following practices appropriate to the 

data category or discipline to archive the underlying data. 

Additionally, the resulting PDF/A-3 files may be too large for convenient dissemination to end users, given that 

most readers will not immediately want to consult the underlying data. 

SPECIFIC SCENARIOS 

U.S. NATIONAL ARCHIVES AND RECORDS ADMINISTRATION (NARA) 

SCENARIOS 

U.S. Government agencies are required to deposit materials appraised as permanently valuable government 

records with the National Archives and Records Administration (NARA). Frequently, agencies store information 

in complex and often proprietary data systems with the permanent records forming only a small subset of the 

complete system. The determination of what digital materials from such systems are considered permanent 

records, and when and in what format they will be transferred is determined by NARA appraisal, accessioning, 

and processing staff and by agency records officers and IT staff. 

The time between appraisal and transfer to NARA can be years or even decades. Hence, federal agencies need 

to plan well in advance of transfer to NARA. Ideally, each agency would consider choosing appropriate formats 

before a record is created and periodically review the format transfer guidance for revisions as part of an overall 

electronic records management plan. 

Many agencies use records management systems built to conform to the Department of Defense Electronic 

Records Management Software Applications Design Criteria Standard (DoD 5015.02-STD).10

 As of late 2013, the 

current version of this standard is from April 2007. A specific set of content types is included in the standard; 

audio and video are not included. 

In the scenarios presented below PDF/A-3 might be determined to be acceptable for legal transfer from an 

agency to NARA. It should be noted that these examples are hypothetical and do not represent current official 

policies. Since PDF/A3 is a recently developed standard, NARA, like most memory institutions, has not 

adequately evaluated the format for its suitability for use when transferring permanent records. 

Scenario for PDF/A3 as an acceptable container for “as -built” engineering 

drawings originating from a CAD system. 

 

10 DoD 5015.02-STD. Electronic Records Management Software Applications Design Criteria Standard, April 25, 2007. 

http://jitc.fhu.disa.mil/cgi/rma/standards.aspx 
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Background and Assumptions: 

One scenario in which NARA might allow for the transfer of permanent digital records in the PDF/A-3 format 

involves exporting a related subset of data and documents from a technical data system that includes 

architectural drawings and computer aided design (CAD) files. In this example, PDF/A-3 is a carrier for 

transferring both the permanent records required by NARA as well as associated non-archival non-permanent 

record content. It should be noted that an alternative scenario might include the agency outputting CAD data as 

a 3D PDF or some other CAD format. The choice of which scenario is “best” depends on what functionality is 

determined to be an inherent part of the record that must be preserved for future researchers. 

Scenario: 

The scenario involves several generalizable steps: 

1. The creating agency contacts the archives regarding the transfer of scheduled permanent electronic records 

from a data system, in this case a CAD system. 

2. NARA appraisal and accessioning staff defines the scope of the system’s record material and identifies PDF/A3 as an appropriate transfer format. 

3. NARA appraisal, accessioning, and processing archivists identify appropriate files and documentation for 

inclusion in the PDF/A-3. 

For this particular hypothetical situation, the NARA recommendation might be as follows. To serve as the 

official as-built drawing copies, a completed set “as-built” drawings resulting from an engineering project will be 

saved as TIFF images and watermarked “AS-BUILT”. The TIFF images are incorporated as primary content in a 

PDF/A-3 document along with the embedded native CAD system working files used to create the drawings. The 

relationship of the native CAD files to the document is to be Source. An appropriate MIME type will be used for 

each embedded file at the time of file creation. 

4. Agency records officer and/or IT staff produce compliant PDF/A-3 files for transfer. 

As agreed, these files have embedded native CAD files and incorporate appropriate relationship codes and 

MIME types. 

5. NARA accessions the PDF/A-3 files as official records and provides preservation actions as needed to the 

page-oriented content of the PDF/A-3. 

After accessioning, NARA would only guarantee the preservation of the page-oriented content of the PDF/A-3, in 

this case the TIFF images of the as-built drawings. In this scenario, the native CAD files would exist only as 

artifacts of the accessioned document. They would not be accorded preservation actions such as migration but 

would be maintained as data. 
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Desirable outcomes and benefits: 

The PDF/A-3 provides a stable container for encapsulating both the official copy as well as files from the original 

system. Encapsulating the original working files along with the official records within a PDF/A-3 provides the 

creating agency a tidy package for successful management of their related files prior to transfer. The transfer of 

the PDF/A-3 meets the records creator’s obligation to NARA that a permanent record of the as-built drawings is 

archived for future reference. 

One additional advantage is realized. The records creator, or other qualified patrons, would be able to re-use 

the technical work for a future design if they have the capability and software to render the native system files. 

The PDF/A-3 file would be a designated record copy in an accepted, unalterable format along with an embedded 

non-official copy in a format primarily used by the record creator during the record’s active use and which 

supports the dynamic manipulation of record’s data. 

With the resulting document NARA is able to preserve, manage, and to provide access to official records. Staff 

and researchers are able to access permanent records from a complex data system in an accessible format. 

Risks and disadvantages: 

The associated embedded data files are in formats that may be not supported in the future and this information 

is vulnerable to loss. 

The native system, non-record files might contain personal information or other sensitive data but would be 

difficult to review by archives staff. 

The relationship between the embedded files may be unclear or erroneous. 

Scenario for PDF/A3 as an acceptable container to circumvent 5015.2 

records management application restrictions. 

Background and Assumptions: 

An agency using a records management system (RMS) that strictly enforces outdated requirements of the DoD 

5015.2 specification is unable to manage long-term temporary records in formats that do not comply with that 

standard. To circumvent this restriction they embed non-conformant audio and video files in PDF/A-3 wrappers 

so that they can be managed in the RMS. 

Scenario: 

The scenario involves several generalizable steps: 

1. The agency has a DoD 5015.2 compliant RMS that restricts the types of formats that can be ingested into it 

based on that standard. 

2. The agency identifies the audio and video records as having long-term temporary value. 
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3. The agency does not consider NARA’s transfer requirements regarding sustainable formats.

Desirable outcomes and benefits: 

Agency staff embeds audio and video files into PDF/A-3 wrappers that can be ingested into their DoD 5015.2 

compliant records management system. 

The agency uses the primary document of the PDF/A-3 to provide narrative context for the embedded audio or 

video. 

Risks and disadvantages: 

The associated embedded data files are in formats that may be not supported in the future and this information 

is vulnerable to loss. Another issue is that the PDF container will make any preservation actions on the 

embedded files (e.g. migration/emulation) more challenging or complex. 

The agency is unable to adequately search for and provide access to the audio and video records embedded in 

the PDF/A-3 files. 

NARA refuses to accept transfer of PDF/A-3 formatted records for audio and video subsequently re-appraised as 

permanent. 

The PDF container adds additional complexity to any required preservation actions for embedded long-termtemporary files. 

LIBRARY OF CONGRESS SCENARIO 

The Library of Congress acquires content for its collections in a number of ways. In only occasional 

circumstances is it able to negotiate actively with a depositing or donating party with respect to digital format. 

The bulk of the general collection is acquired through copyright deposit, for which preferred or acceptable 

digital formats are listed in a document published by the U.S. Copyright Office as Copyright Circular 7b: “Best 

Edition” of Published Copyrighted Works for the Collections of the Library of Congress.

11

 Collections of personal 

or organizational "papers" are usually donated as is. Content harvested from the Web for archiving is usually 

only available in one format. 

Scenario for harvesting PDF documents from the web and converting to 

PDF/A-3 

Background and Assumptions: 

The Library of Congress has a pilot program harvesting and cataloging documents in PDF format from the web, 

when a recommending officer has identified the work as fitting LC collection policies for books. One typical use 

 

11 U. S. Copyright Office, Library of Congress, “Best Edition of Published Copyrighted Works for the Collections of the Library 

of Congress http://www.copyright.gov/circs/circ07b.pdf 
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is for documents published outside the U.S. and not subject to U.S. copyright deposit. For these, permission to 

harvest and archive is sought from the publishing website. Another use being explored is for PDFs that have 

embedded Creative Commons licenses, or equivalent, that permit non-commercial use with attribution. There is 

no opportunity for the Library of Congress to negotiate with the content owner over the characteristics of the 

PDF. 

Scenario: 

A possible workflow for ingestion includes conversion of source PDFs to PDF/A. This would allow fonts to be 

embedded (assuming fonts used were available and legally embeddable) and permit addition of metadata that 

supports Library of Congress services for access and preservation. Current experiments use PDF/A-1, but PDF/A3 files could potentially be used with the source PDF embedded inside the modified PDF. A relationship type of 

Source (to the entire document) and a MIME type of application/pdf would be used for the embedded 

file. 

Desirable outcomes and benefits: 

The modified PDF/A file (without the embedded source) is in a form that has desirable characteristics (such as 

embedded fonts) for supporting both current access and for maintaining long-term usability of the content in 

the source PDF. 

The PDF/A-3 resource (with the embedded source document) can be managed as a single master file and used 

to derive a smaller service PDF for dissemination to users. 

Future users requiring assurance of the authenticity of the disseminated version can be given access to the 

source PDF as well. 

Risks and disadvantages: 

The PDF/A-3 with embedded source document will be larger than the original source file and may be 

inconvenient as a file for user access, for example on mobile devices. This leads to the need for storing multiple 

versions or for building dissemination systems that derive service PDFs on the fly. 

Some source PDF documents will incorporate features prohibited in PDF/A, for example, a font subject to a 

license that prohibits embedding. This will prevent conversion to PDF/A and hence to PDF/A-3 for some source 

PDFs. This leads to a more complicated ingestion workflow with more opportunities for error. 

Without more robust validation tools than available in 2013, the conversion to PDF/A and PDF/A-3 may be 

unreliable.12

 

12 Jamin Koo and Carol C. H. Chou. “PDF to PDF/A: Evaluation of Converter Software for Implementation in Digital Repository 

Workflow.” New Review of Information Networking Vol. 18, Iss. 1, 2013. Available at 

http://www.tandfonline.com/doi/full/10.1080/13614576.2013.771989 
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U.S. HOUSE OFFICE OF THE LEGISLATIVE COUNSEL (HOLC) SCENARIOS 

The Office of the Legislative Counsel provides legislative drafting services to the committees and Members of 

the House of Representatives on a non-partisan, impartial, and confidential basis. The goal is to work with 

committees and Members to understand their policy preferences in order to implement those preferences 

through clear, concise, and legally effective legislative language. 

The two scenarios that follow are based on discussions with Joe Carmel, Retired Chief, Legislative Computer 

Systems and contractor, U.S. House Office of the Legislative Counsel and Reynold Schweickhardt, Director of 

Technology Policy, Committee on House Administration. These scenarios concern the use of PDF/A-3 for 

internal workflows. They are not directly related to processes and policies that apply to public access to 

published legislative information. 

Scenario for embedding source files as an aid to maintain attorney-client 

confidentiality 

Background and Assumptions: 

The House Office of the Legislative Counsel (HOLC) maintains attorney-client confidentiality. While the office 

routinely provides Members and their staff with PDF files, the House’s process requires that some of the source 

files subsequently be made available to other House offices. 

The legislative drafting and publication system is based on XML, from which PDF documents are generated for 

convenient reading. 

Scenario: 

HOLC prepares a draft amendment for an individual Member and generates a PDF document for convenient 

review. HOLC chooses to generate a PDF/A-3 file with the equivalent XML embedded in the PDF, using the 

relationship Source to associate the embedded file with the entire primary document. The Member reviews 

the PDF and judges that the amendment is ready for sharing with another office, which will need access to the 

source XML file for subsequent stages in the legislative workflow. The Member sends the file he received from 

HOLC. 

[Note: the process of embedding XML source is in current use, but as of late 2013, the PDF file is not a PDF/A-3 

file. Files with embedded attachments (primarily amendments) can be seen at the House Rules Committee 

website. An example is http://www.rules.house.gov/amendments/DELAMD_002_xml318131552385238.pdf.]

Desirable outcomes and benefits: 

Emailing a single PDF file with an embedded source file enables HOLC to maintain attorney-client confidentiality 

since the client (a Member) can subsequently provide the PDF file to other House offices requiring access to the 

source XML for future action. 

The potential for mismatching two files (PDF and XML source) due to human error is eliminated. 
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Risks and disadvantages: 

None identified, since the process for creating the PDF and embedding the source XML is automated and 

guarantees equivalence. 

Scenario for embedding XML files to align PDF page/line locations with 

XML when editing amendments 

Background and Assumptions: 

A project still in development known as the Amendment Impact Program (AIP) is being designed to show the 

impact of an amendment on a bill based on separate amendment document language. 

Page-numbering for bills is applied when the human-readable versions are derived from the source XML. A 

sample amendment instruction might be: On page 6, line 5, insert “motivated” before “Congress”. This 

processing cannot be accomplished without having both the PDF and source files available as the PDF files 

contain the page and line numbers while the source documents do not incorporate page-numbering 

Scenario: 

A PDF/A-3 file with embedded XML is constructed for a bill. The proposed project would develop a system to 

take this file and amendment files and generate revised XML source. 

Desirable outcomes and benefits: 

The PDF/A-3 with embedded XML source can be generated and transmitted, assuring that the PDF rendition and 

the source XML are correctly matched. 

The combination of the PDF and XML source file permits matching the page/line locations from the PDF file to 

the correct location within the source XML file. 

Risks and disadvantages: 

None identified, since the process for creating the PDF and embedding the source XML is automated and 

guarantees equivalence. 

CONCLUSIONS 

The most important characteristic of the PDF/A formats is that they are constrained in ways that are designed to 

preserve the "static visual appearance" of a page-oriented document. The differences between PDF/A-1 (2005) 

and PDF/A-2 (2011) relate primarily to the fact that they are based on different generations of the underlying 

PDF specification. The overarching intent did not change; the entire file was intended to be suitable for longterm preservation. PDF/A-1 and PDF/A-2 are both suitable for long-term preservation, although they would not 

necessarily be the preferred format for any particular content item. The introduction of arbitrary embedded 

files to PDF/A-3 introduces significant concerns for memory institutions. A PDF/A-3 file may have any other type 
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of file embedded within it and the only statement that the standard makes in relation to preservation intent is 

that a compliant PDF/A-3 reader should not render embedded files, but merely support their extraction. The 

standard is silent as to whether the embedded content may be considered essential to full understanding or use 

of the primary document whose visual appearance is preservable. The result is that, accepting a PDF/A-3 file 

without additional rules or active negotiation, may lead an archival institution to acquire embedded content in a 

format that it did not expect and cannot deal with and whose relationship to the primary document may be 

unclear. 

The members of this working group recognize that the PDF/A-3 format serves important business needs 

unrelated to preservation for the long term. One general application is the inclusion of structured machinereadable information within a PDF that is intended for viewing by a human with visual appearance retained 

across computing systems. Many workflows or transactions that have no relationship to long-term preservation 

can benefit from this capability. Another general application is known as "hybrid archiving." The context is that 

an entity such as a corporation is required to "archive" certain categories of document for a certain period to 

satisfy government regulations. These documents start life in an editable form and at some stage are deemed 

to be final; if intermediate drafts are saved as PDF/A-3 with the editable form embedded, the document is 

archivable at any stage, simplifying records management. These business needs are driving the development of 

tools for creating PDF/A-3 files. Some will certainly be deposited with memory institutions. 

The complexity of the PDF format and the potential and actual resulting faultiness of PDF rendering 

implementations and creating applications suggest that PDF/A-3 may be most appropriate for use in controlled 

workflows, but may not be an appropriate choice as a general-purpose bundling format. 

However, the proposed creation by the PDF Association of a free and open source PDF validation tool might 

mitigate the long-term preservation risks constituted by the complexity of the PDF/A format as a bundling 

format. Absent such robust validation tools, conversion of PDF files to PDF/A in preservation workflows remains 

a somewhat problematic preservation tactic. 

Further, should the consensus of the preservation community be that PDF/A-3 is inappropriate as a generalpurpose archival bundling format, then the community must identify and/or create tools that make it possible to 

bundle together complex digital objects with sufficient manifest information (i.e. metadata) to establish the 

relationship amongst the components within the bundle. 

Such a bundling format might usefully be based on the BagIt File Packaging Format13 and/or a constrained form 

of the ZIP format, such as the proposed ISO/IEC 21320-1 “Document Container File” specification14 (as of 

December 2013, this standard is in the Committee Draft stage). ISO/IEC 21320-1 is intended to be a formallyspecified interoperable and royalty-free subset of the proprietary ZIP format developed and maintained by 

PKWARE. BagIt is a hierarchical file packaging format for storage and transfer of arbitrary digital content. A 

typical serialization as a single file is based on ZIP or TAR. 

 

13 The BagIt File Packaging Format (V0.97). Available at http://www.digitalpreservation.gov/documents/bagitspec.pdf 

14 ISO/IEC CD 21320-1.2, Information technology -- Document Container File -- Part 1: Core. Available (as committee draft) 

at http://isotc.iso.org/livelink/livelink?func=ll&objId=15629477&objAction=Open&viewType=1. Final version, when 

published, will be available at http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=60101 
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Since PDF/A creation tools may generate files that identify themselves as PDF/A-3 even when no files are 

embedded, one recommended triage step for PDF/A-3 during ingest is to check whether a PDF/A-3 file has any 

embedded files. If no files are embedded then a PDF/A-3 can be treated in the same way as PDF/A-1 and PDF/A2 files in a preservation ingest workflow. The working group strongly recommends that tools that create PDF/Acompliant documents be engineered to identify (through the pdfaid:part element) files that have no embedded 

files, or whose embedded files are all in PDF/A format, as compliant with PDF/A-2 rather than PDF/A-3.

Memory institutions and archival repositories should be prepared to treat PDF/A-3 files with care and develop 

procedures that fit their overall mission and policies. How embedded files should be treated depends on the 

context for creation, the expressed relationships that embedded files have to the primary document, the 

expectations of future users, and the policies of the archiving institution. 

Operational elements of archival strategies often include (a) a list of preferred and acceptable formats with 

associated levels of commitment or confidence with respect to long-term preservation and access and (b) action 

plans for each format that govern procedures on ingest. Many institutions have given PDF/A a high priority on 

such lists and assumed that files that comply with the PDF/A-1 and PDF/A-2 standards require no normalization 

on ingest. PDF/A-3 must be treated separately from the other PDF/A versions in preference lists and for action 

plans. 

The introduction of such a problematic new feature in the latest version of the PDF/A family suggests that 

perhaps the community of memory institutions need to take a more strategic, active, and vocal role in the 

standards development process. 
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APPENDIX A: RESOURCES AND REFERENCES 

Adobe Systems Incorporated. PDF Reference, Third Edition, Version 1.4. Addison-Wesley, 2001. ISBN: 0-201-

75839-3. Also available online at 

http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/pdf_reference_arch

ives/PDFReference.pdf. 

Adobe Systems Incorporated. Document Management – Portable Document Format – Part 1: PDF 1.7, First 

Edition. Jul 2008. Available at 

http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/PDF32000_2008.pd

f

Caroline R. Arms and Carl Fleischhauer. “Sustainability of Digital Formats: Planning for Library of Congress 

Collections.” Available at http://www.digitalpreservation.gov/formats/ 

The BagIt File Packaging Format (V0.97). Available at 

http://www.digitalpreservation.gov/documents/bagitspec.pdf

Digital Preservation Coalition, "Digital Preservation with Portable Documents: a workshop to introduce and 

discuss the PDF/A version." Available at http://www.dpconline.org/events/details/55-

DPC_PDFA3_briefing?xref=58

DoD 5015.02-STD. Electronic Records Management Software Applications Design Criteria Standard, April 25, 

2007. Available at http://jitc.fhu.disa.mil/cgi/rma/standards.aspx 

German ZUGFeRD Format for electronic Invoices. Available at http://www.pdflib.com/knowledgebase/pdfa/zugferd-invoices/

ISO 32000-1:2008 Document management -- Portable document format -- Part 1: PDF 1.7 Available at 

http://www.iso.org/iso/catalogue_detail?csnumber=51502

ISO 19005-1:2005 Document management -- Electronic document file format for long-term preservation -- Part 

1: Use of PDF 1.4 (PDF/A-1) Available at 

http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=38920

ISO 19005-2:2011 Document management -- Electronic document file format for long-term preservation -- Part 

2: Use of ISO 32000-1 (PDF/A-2). Available at 

http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=50655

ISO 19005-3:2012 Document management -- Electronic document file format for long-term preservation -- Part 

3: Use of ISO 32000-1 with support for embedded files (PDF/A-3). Available at 

http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=57229

ISO/IEC CD 21320-1.2, Information technology -- Document Container File -- Part 1: Core. Available (as 

committee draft) at 
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http://isotc.iso.org/livelink/livelink?func=ll&objId=15629477&objAction=Open&viewType=1. Final version, 

when published, will be available at 

http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=60101

Jamin Koo and Carol C. H. Chou. “PDF to PDF/A: Evaluation of Converter Software for Implementation in Digital 

Repository Workflow.” New Review of Information Networking Vol. 18, Iss. 1, 2013. Available at 

http://www.tandfonline.com/doi/full/10.1080/13614576.2013.771989

Butch Lazorchak. "All In! Embedded Files in PDF/A" posted on The Signal Digital Preservation Blog, Nov.13, 

2012. Available at http://blogs.loc.gov/digitalpreservation/2012/11/all-in-embedded-files-in-pdfa/

Sheila M. Morrissey, "The Network is the Format: PDF and the Long-term Use of Digital Content" in Proceedings 

of Archiving 2012, Volume 8 (June 2012). Available at http://www.portico.org/digital-preservation/wpcontent/uploads/2012/12/Archiving2012TheNetworkIsTheFormat.pdf

PDF/A Competence Center. Available at http://www.pdfa.org/competence-centers/pdfa-competence-center/

PDF Association. Available at http://www.pdfa.org/pdf-association/

U. S. Copyright Office, Library of Congress, “Best Edition of Published Copyrighted Works for the Collections of 

the Library of Congress. Available at http://www.copyright.gov/circs/circ07b.pdf
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GLOSSARY

Associated file 

See Embedded file. 

Bundling format 

Digital format designed to aggregate a collection of related digital files into a single file for convenience of 

transmission or storage. [Note: the most widely used bundling format is ZIP. In contrast to wrapper formats, 

files encapsulated in bundling formats are often explicitly extracted as individual files before use. 

CAD

Computer-aided design. 

CSV 

Comma-separated values (file format). 

Embedded file 

File stored inside a PDF/A-3 document in compliance with ISO 19005-3.

File Specification Dictionary 

Data structure defined in the PDF specification, used in PDF/A-3 to relate embedded files to the document as a 

whole or specific sections of content. 

GIS 

Geospatial information system . 

ISO 

International Organization for Standardization. 

ISO 19005-1 

Specification of PDF/A-1 (2005). 

ISO 19005-2 

Specification of PDF/A-2 (2011). 

ISO 19005-3 
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Specification of PDF/A-3 (2012). 

MIME type 

Value for a media type code, as assigned by IANA. [See http://www.iana.org/assignments/media-types ].

PDF

Portable Document Format, file format defined in ISO 32000-1:2008 or Adobe PDF Reference 1.4. 

PDF/A-1 

Restricted subset of PDF, based on Adobe PDF Reference 1.4, as defined in ISO 19005-1:2005. 

PDF/A-2 

Restricted subset of PDF, as defined in ISO 19005-2:2011. 

PDF/A-3 

Restricted subset of PDF, as defined in ISO 19005-3:2013. 

Primary Document 

The content representing the page-oriented document as would be presented through a conforming interactive 

PDF/A-3 reader, not including any embedded files. 

Transparency 

The degree to which the digital representation is open to direct analysis with basic tools. [See 

http://www.digitalpreservation.gov/formats/sustain/sustain.shtml - transparency ].

Wrapper format 

Digital file format designed as an envelope for one or more streams of related digital content, where the stream 

format is specified independently. [Note: For example, the QuickTime format is a wrapper that typically 

contains audio or video bitstreams, which may conform to one of many compression encodings. In contrast to 

bundling formats, files compliant with a wrapper specification are typically used as is by a reader/player that 

understands both the wrapper and the encoding of encapsulated bitstreams.] . 

XML

Extensible Markup Language.