PDF Standards

PDF is not just one format — it is a family of ISO standards, each designed for a specific use case. This page covers the major PDF standards, their differences, and when to use each.

PDF/A — Long-Term Archival

PDF/A (ISO 19005) is the standard for long-term preservation of electronic documents. It ensures that a PDF will look the same 10, 50, or 100 years from now, regardless of the software used to open it.

PDF/A achieves this by requiring:

• All fonts embedded in the document
• No external dependencies (no linked images, no JavaScript)
• ICC color profiles for consistent color reproduction
• XMP metadata for document identification

PDF/A Versions

There are four generations of PDF/A, each based on a different PDF version:

PDF/A Conformance Levels

Each PDF/A version comes in different conformance levels:

In practice, level b (basic) is what most organizations need. Level a requires a fully tagged document structure, which is difficult to achieve with generated documents.

Which PDF/A Version Should I Use?

• PDF/A-3b is the recommended choice for most use cases. It is modern, supports CSS transparency, and allows file attachments (required for e-invoicing).
• PDF/A-2b if you do not need file attachments.
• PDF/A-1b only if required by a legacy system that does not accept newer versions.

PDF/A and TemplateFox

TemplateFox supports PDF/A-1b, PDF/A-2b, and PDF/A-3b generation via the pdf_variant parameter in the PDF generation API.

curl -X POST https://api.pdftemplateapi.com/v1/pdf/create \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "template_id": "HMQywVpZxqAM",
    "data": { "invoice_number": "INV-001" },
    "pdf_variant": "pdf/a-3b"
  }'

No changes to your templates are needed. The same template works for both standard PDF and PDF/A output.

Factur-X and ZUGFeRD — Electronic Invoicing

Factur-X (France) and ZUGFeRD (Germany) are the same standard for hybrid electronic invoices. A Factur-X invoice is a PDF/A-3 document with a structured XML file embedded inside it.

This means the invoice is both:

• Human-readable — the PDF looks like a normal invoice
• Machine-readable — the embedded XML can be parsed by accounting software automatically

Factur-X is based on the European standard EN 16931 and is becoming mandatory for B2B invoicing across the EU:

• France: Mandatory for large companies from September 2026, all companies by 2027
• Germany: Mandatory for B2B from January 2025 (receiving), 2027 (sending)
• Italy: Already mandatory since 2019 (FatturaPA, a different format)

Factur-X Profiles

Generating Factur-X with TemplateFox

To create a Factur-X invoice, you need two things:

1. PDF/A-3 output — set pdf_variant to "pdf/a-3b" in the API call
2. XML attachment — the structured invoice data (Factur-X XML generation is not yet built into TemplateFox, but the PDF/A-3 foundation is ready)

PDF/X — Print Production

PDF/X (ISO 15930) is designed for prepress and commercial printing. It ensures reliable color reproduction and print-ready output.

Key differences from PDF/A:

• PDF/X is about accurate color and print reproduction, not long-term archival
• PDF/X requires specific output intents (color profiles for the target printer)
• PDF/X is used by print shops, publishers, and packaging companies

PDF/X is not currently supported by TemplateFox. If you need print-ready output, export as standard PDF and use a dedicated prepress tool.

PDF/UA — Universal Accessibility

PDF/UA (ISO 14289) is the standard for accessible PDF documents. It ensures that PDFs can be read by screen readers and other assistive technologies.

Key requirements:

• Every element must be tagged (headings, paragraphs, lists, tables)
• Images must have alternative text
• Reading order must be defined
• Language must be specified

PDF/UA is important for government, education, and healthcare where accessibility compliance (WCAG, Section 508, EN 301 549) is required.

PDF/UA is not currently supported by TemplateFox.

PDF/E — Engineering

PDF/E (ISO 24517) is designed for engineering documents — technical drawings, CAD output, and 3D models.

PDF/E is a niche standard used primarily in manufacturing, architecture, and aerospace. It is not relevant for typical document generation.

Comparison Table

Common Questions

Can a PDF be both PDF/A and PDF/UA?

Yes. A document can conform to multiple standards simultaneously. For example, a PDF/A-2a document that is also PDF/UA-1 compliant is both archival and accessible.

Does PDF/A increase file size?

Slightly. PDF/A requires all fonts to be fully embedded rather than subsetted, which can increase file size by 10-50% depending on the number of fonts used. This is a trade-off for long-term reproducibility.

Can I convert an existing PDF to PDF/A?

Converting after the fact is possible but unreliable — missing fonts cannot be recovered, and the conversion tool must guess at color profiles. It is much better to generate PDF/A from the source, which is what TemplateFox does.

Is PDF/A the same as “archiving a PDF”?

No. Saving a regular PDF to a folder is not the same as PDF/A compliance. A regular PDF may reference external fonts, use features that are deprecated, or lack the metadata required for long-term preservation. PDF/A guarantees self-containedness.