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

Purpose Summary

This page explains how Aspose.Words converts documents to PDF/A and PDF/UA formats, outlining supported compliance levels and conversion specifics.

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 the following articles, 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

• Convert a Document to PDF
• 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

Related APIs

• PdfSaveOptions
• PdfCompliance

---

FAQ

1. Q: How do I convert a document to PDF/A‑2 using Aspose.Words for .NET?
   A: Create a PdfSaveOptions object, set its Compliance property to PdfCompliance.PdfA2b (or PdfA2a/PdfA2u depending on the required level), and pass the options to the Document.Save method. Example:

   Document doc = new Document("input.docx");
   PdfSaveOptions options = new PdfSaveOptions();
   options.Compliance = PdfCompliance.PdfA2b;
   doc.Save("output.pdf", options);
   

2. Q: What are the main differences between PDF/A‑1, PDF/A‑2 and PDF/A‑4 compliance levels?
   A: PDF/A‑1 forbids transparency, certain compression methods, and requires all fonts to be embedded. PDF/A‑2 relaxes these restrictions, allowing transparency, layer effects, and OpenType font embedding. PDF/A‑4 introduces revised conformance levels: “U” (unrestricted) aligns with earlier versions, while the “A” level has been removed, simplifying the standard.

3. Q: How can I ensure the generated PDF/A file complies with font‑embedding and encryption requirements?
   A: Set options.Compliance to the desired PDF/A level; Aspose.Words automatically embeds all used fonts. To avoid encryption, do not set any password or encryption options on the PdfSaveOptions. If you previously set a password, clear it before saving.

4. Q: Is there anything extra I need to do to create a PDF/UA‑1 compliant document?
   A: Use PdfSaveOptions.Compliance = PdfCompliance.PdfUAX (or the appropriate enum value for PDF/UA‑1). Ensure the source document contains proper heading styles, alt text for images, and language attributes, because PDF/UA requires a fully tagged PDF. Aspose.Words will generate the required tags when the compliance is set.

5. Q: Does the Aspose.Words license affect PDF/A or PDF/UA conversion?
   A: No. The license controls feature availability (e.g., removing evaluation watermarks) but does not change how compliance levels are applied. As long as the library is licensed, you can use any supported PDF/A or PDF/UA compliance option without restrictions.