Learn Features of Conversion to PDF/A and PDF/UA

PDF is a fixed page format that is very popular among users and is widely supported by various applications, as a PDF document looks the same on any device. For this reason, converting to PDF is an important feature of Aspose.Words.

PDF is a complex format by itself, as it has a specific file structure, graphical model, font embedding, and some complex output functionality such as document structure tags, encryption, digital signatures, and editable forms. In addition, converting a document to PDF requires several calculation stages, which are complex and time-consuming.

In this section, we will consider the main problems that may arise when working with documents in various PDF standards and describe options for solving them.

Which PDF Standard Aspose.Words Supports

Aspose.Words now allows users to work with PDF/A-1, PDF/A-2 and PDF/A-4 formats, as well as PDF/UA-1:

• PDF/A-1 has serious limitations such as transparency and some compression options are prohibited
• PDF/A-2 eliminates some of the limitations of PDF/A-1, such as support of transparency and layer effects or embedding of OpenType fonts
• PDF/A-4 assumes revised conformance levels: regular PDF/A-4 conformance is equivalent to previous versions' level U conformance, and the level A conformance is removed
• PDF/UA-1 content should be tagged and standardized according to ISO 32000-1: 2008

PDF/A is an ISO-standardized version of PDF intended for use in archiving and long-term storage of electronic documents. At the same time, PDF/UA is another ISO standardized version of PDF designed to ensure accessibility for people with disabilities who use assistive technology. To specify the level of compliance with PDF standards, use the Compliance property. Due to storage conditions, PDF/A document must embed all fonts and disable encryption, while PDF/UA must only embed all fonts.

In this section, we will take a closer look at working with PDF/A or PDF/UA-1 documents.

Relevant ISO for PDF Standards

To learn more about the different PDF standards, check the following ISOs:

• PDF 1.7 = ISO-32000-1: 2008
• PDF 2.0 = ISO-32000-2: 2020
• PDF/A-1 = ISO-19005-1: 2005
• PDF/A-2 = ISO-19005-2: 2011
• PDF/A-4 = ISO-19005-4: 2020
• PDF/UA-1 = ISO-14289: 2014

See Also

• How to edit document structure tags in Adobe Acrobat
• How to check or edit text language in Microsoft Word
• How to change text language in Adobe Acrobat
• How to add alternative text to a shape, picture, chart, SmartArt graphic, or other object in Microsoft Word
• How to add alternate text and supplementary information to tags (or read the same information in the Adobe Acrobat User Guide)
• How to set up ActualText entry for text, the “Add Actual Text for an Abbreviated Term, Formula, or Non‑Unicode Symbol” section
• Unicode mapping for common Windows symbolic fonts

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FAQ

1. Q: How do I set the PDF/A or PDF/UA compliance level when saving a document with Aspose.Words for C++?
   A: Create a PdfSaveOptions object, set its Compliance property to the desired enum value (PdfCompliance::PdfA1b, PdfCompliance::PdfA2b, PdfCompliance::PdfA4, or PdfCompliance::PdfUa1), and pass the options to the Document::Save method. Example:

   Aspose::Words::Document doc(u"input.docx");
   Aspose::Words::Saving::PdfSaveOptions options;
   options.set_Compliance(Aspose::Words::Saving::PdfCompliance::PdfA2b);
   doc.Save(u"output.pdf", options);
   

2. Q: Do I need to embed all fonts manually for PDF/A compliance?
   A: No. When you set a PDF/A compliance level, Aspose.Words automatically embeds all fonts used in the document. You can control font substitution via FontSettings if required, but explicit embedding is not necessary.

3. Q: Can I encrypt a PDF/A document? What happens if I try?
   A: PDF/A specifications prohibit encryption. If you set a PDF/A compliance level and also enable encryption (e.g., options.set_EncryptionDetails(...)), Aspose.Words will ignore the encryption settings and generate an unencrypted PDF/A file, ensuring the document remains compliant.

4. Q: How can I verify that the generated PDF meets the selected PDF/A or PDF/UA standard?
   A: After saving, you can use a PDF validation tool (such as Adobe Acrobat Preflight or the open‑source VeraPDF) to check conformance. Aspose.Words does not perform post‑save validation, so an external validator is required for certification.

5. Q: What are the main differences between PDF/A‑1, PDF/A‑2, and PDF/A‑4 regarding transparency and font handling?
   A:

   • PDF/A‑1 forbids transparency and limits compression; all fonts must be embedded as Type 1 or TrueType.
   • PDF/A‑2 allows transparency, layer effects, and supports OpenType fonts, providing more modern layout capabilities.
   • PDF/A‑4 builds on PDF/A‑2 but aligns with PDF 2.0, removing the “Level A” conformance variant and keeping the “Level U” (basic) conformance. All three require full font embedding, but only PDF/A‑2 and PDF/A‑4 support transparent objects.