Difference between revisions of "PDF/A in PDS4 - A Primer"
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== PDF/A Overview == | == PDF/A Overview == | ||
− | There are | + | The Portable Document Format (PDF) is a broad, complex file format. The International Organization for Standardization (ISO) has created various PDF subset standards which are specialized for different uses. The PDF/A standard (ISO 19005) is designed for long-term preservation. There are three iterations of the PDF/A standard so far: PDF/A-1, PDF/A-2, and PDF/A-3. Versions of PDF/A retain backward but not forward compatibility (e.g., a document that complies with PDF/A-2 will also conform to PDF/A-3, but not necessarily to PDF/A-1). PDS4 requires compliance specifically to the first version, PDF/A-1.<ref>[https://pds.jpl.nasa.gov/policy/format_policies_final.pdf ''Policy on Formats for PDS4 Data and Documentation'']. (2014, June 30). The Planetary Data System. From [https://pds.jpl.nasa.gov/policy/ PDS Policies]</ref> |
+ | |||
=== PDF/A-1 === | === PDF/A-1 === | ||
− | PDF/A-1 is based on PDF | + | PDF/A-1 (ISO 19005-1) is based on PDF Version 1.4, and imposes further specifications. |
: PDF/A-1 files '''must''' include: | : PDF/A-1 files '''must''' include: | ||
− | :* Embedded fonts<ref name="FAQ">[http://www.npes.org/pdf/19005-1_FAQ.pdf 19005-1 FAQ]. (2006, July 10). PDF/A Joint Working Group. From [http://www.npes.org/programs/standardsworkroom/toolsbestpractices/pdfa.aspx NPES PDF/A FAQ]</ref> | + | :* Embedded fonts <ref name="FAQ">[http://www.npes.org/pdf/19005-1_FAQ.pdf ''19005-1 FAQ'']. (2006, July 10). PDF/A Joint Working Group. From [http://www.npes.org/programs/standardsworkroom/toolsbestpractices/pdfa.aspx NPES PDF/A FAQ]</ref> |
− | :* Device-independent color<ref name="FAQ"/> | + | :* Device-independent color <ref name="FAQ"/> |
− | :* XMP metadata<ref name="FAQ"/> | + | :* XMP metadata <ref name="FAQ"/> |
: PDF/A-1 files '''may not''' include: | : PDF/A-1 files '''may not''' include: | ||
− | :* Encryption<ref name="FAQ"/> | + | :* Encryption <ref name="FAQ"/> |
− | :* LZW Compression<ref name="FAQ"/> | + | :* LZW Compression <ref name="FAQ"/> |
− | :* Embedded files<ref name="FAQ"/> | + | :* Embedded files <ref name="FAQ"/> |
− | :* External content references<ref name="FAQ"/> | + | :* External content references <ref name="FAQ"/> |
− | :* PDF Transparency<ref name="FAQ"/> | + | :* PDF Transparency <ref name="FAQ"/> |
− | :* Multi-media<ref name="FAQ"/> | + | :* Multi-media <ref name="FAQ"/> |
− | :* JavaScript<ref name="FAQ"/> | + | :* JavaScript <ref name="FAQ"/> |
+ | There are two levels of conformance: | ||
+ | :; PDF/A-1b — Level B (Basic) Conformance | ||
+ | :* This is the minimum conformance level required for PDS4. | ||
+ | :; PDF/A-1a — Level A (Accessible) Conformance | ||
+ | :* This is the much preferred conformance level for PDS4. | ||
− | + | Note that it's not immediately apparent whether a PDF file conforms to a standard. All PDF documents are defined by the same file format, after all, and thus they all use the <code>.pdf</code> filename extension. A document that is intentionally standard-compliant should, however, have metadata which specifies its standard. A file which claims to conform to PDF/A-1a, for example, will include the following tags in the <code>pdfaid</code> namespace: | |
− | + | {| width=0% | |
− | + | |<pre> | |
− | + | <pdfaid:part>1</pdfaid:part> | |
− | + | <pdfaid:conformance>A</pdfaid:conformance></pre> | |
− | + | |} | |
+ | A PDF reader may make note of this designation. Adobe Acrobat, in particular, displays a blue banner which states that the file "claims compliance with the PDF/A standard." Regardless, this claim of compliance must be [[Creating and Validating PDF/A-1 Documents#Validation|validated]]. A non-compliant document may incorrectly have metadata indicating compliance; conversely, compliance metadata may be missing from an otherwise compliant document. | ||
== See Also == | == See Also == |
Revision as of 19:48, 7 July 2017
PDF/A Overview
The Portable Document Format (PDF) is a broad, complex file format. The International Organization for Standardization (ISO) has created various PDF subset standards which are specialized for different uses. The PDF/A standard (ISO 19005) is designed for long-term preservation. There are three iterations of the PDF/A standard so far: PDF/A-1, PDF/A-2, and PDF/A-3. Versions of PDF/A retain backward but not forward compatibility (e.g., a document that complies with PDF/A-2 will also conform to PDF/A-3, but not necessarily to PDF/A-1). PDS4 requires compliance specifically to the first version, PDF/A-1.[1]
PDF/A-1
PDF/A-1 (ISO 19005-1) is based on PDF Version 1.4, and imposes further specifications.
- PDF/A-1 files must include:
- PDF/A-1 files may not include:
There are two levels of conformance:
- PDF/A-1b — Level B (Basic) Conformance
- This is the minimum conformance level required for PDS4.
- PDF/A-1a — Level A (Accessible) Conformance
- This is the much preferred conformance level for PDS4.
Note that it's not immediately apparent whether a PDF file conforms to a standard. All PDF documents are defined by the same file format, after all, and thus they all use the .pdf
filename extension. A document that is intentionally standard-compliant should, however, have metadata which specifies its standard. A file which claims to conform to PDF/A-1a, for example, will include the following tags in the pdfaid
namespace:
<pdfaid:part>1</pdfaid:part> <pdfaid:conformance>A</pdfaid:conformance> |
A PDF reader may make note of this designation. Adobe Acrobat, in particular, displays a blue banner which states that the file "claims compliance with the PDF/A standard." Regardless, this claim of compliance must be validated. A non-compliant document may incorrectly have metadata indicating compliance; conversely, compliance metadata may be missing from an otherwise compliant document.
See Also
External Links
- General
- Backend
- Buy ISO PDF/A-1 Standard:
References
- ↑ Policy on Formats for PDS4 Data and Documentation. (2014, June 30). The Planetary Data System. From PDS Policies
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 19005-1 FAQ. (2006, July 10). PDF/A Joint Working Group. From NPES PDF/A FAQ