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, PDF/A-3, and PDF/A-4 formats, as well as PDF/UA-1 and PDF/UA-2:

• 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-3 allows embedding of attachments into a PDF document and enables richer document workflows, such as archiving of associated source data alongside visual content
• 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/UA-2 improves accessibility support with enhanced tagging structures, better support for modern PDF features, and alignment with WCAG guidelines

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 PdfSaveOptions.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-3 = ISO 19005-3: 2012
• PDF/A-4 = ISO-19005-4: 2020
• PDF/UA-1 = ISO-14289: 2014
• PDF/UA-2 = ISO 14289-2:2024

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