Standards and Conformance

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PDF/A Archival

tc-lib-pdf supports PDF/A output for long-term archival workflows (ISO 19005). Pass the mode string as the mode argument to the Tcpdf constructor:

// PDF/A-1b (default conformance level when suffix is omitted)
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa1');

// Explicit conformance levels
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa1a');  // PDF/A-1a
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa1b');  // PDF/A-1b
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa2a');  // PDF/A-2a
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa2b');  // PDF/A-2b
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa2u');  // PDF/A-2u
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa3a');  // PDF/A-3a
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa3b');  // PDF/A-3b
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa3u');  // PDF/A-3u

Mode suffix	Conformance	Unicode ToUnicode	Tagged structure
a	Level A	required	required
b	Level B	required	not required
u	Level U (parts 2/3 only)	required	not required

PDF/A-3 supports embedding arbitrary file attachments (for example XML invoice payloads). This is the basis for Factur-X / ZUGFeRD workflows - embed the structured XML in a PDF/A-3 document and register the relationship via XMP metadata:

$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa3');
// ... build document ...
$pdf->addContentAsEmbeddedFile(
    file: 'factur-x.xml',
    content: $invoiceXML,
    mime: 'text/xml',
    afrel: \Com\Tecnick\Pdf\AFRelationship::Alternative,
);
$pdf->setCustomXMP('x:xmpmeta.rdf:RDF.rdf:Description.pdfaExtension:schemas.rdf:Bag', $xmpBag);

Runnable example (invoice with embedded Factur-X XML): examples/E001_invoice.php.

PDF/X Conformance

tc-lib-pdf supports multiple PDF/X profiles for print-exchange workflows. Pass the mode string as the mode argument to the Tcpdf constructor:

// Generic PDF/X alias (maps to the library's baseline print-exchange workflow)
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfx');

// Specific variants
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfx1a'); // PDF/X-1a:2003
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfx3');  // PDF/X-3:2003
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfx4');  // PDF/X-4:2010
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfx5');  // PDF/X-5g:2010

Each variant automatically applies the appropriate conformance constraints:

Mode	Min PDF version	Transparency	Process colors	GTS_PDFXVersion
pdfx / pdfx3	1.3	blocked	CMYK forced	PDF/X-3:2003
pdfx1a	1.3	blocked	CMYK forced	PDF/X-1a:2003
pdfx4	1.6	allowed	unrestricted	PDF/X-4:2010
pdfx5	1.6	allowed	unrestricted	PDF/X-5g:2010

All PDF/X modes suppress encryption and JavaScript (not permitted by the ISO 15930 standard).

Runnable examples: examples/E010_pdfx.php through examples/E014_pdfx5.php.

PDF/UA Accessibility

tc-lib-pdf supports tagged PDF output conforming to PDF/UA (ISO 14289). Pass the mode string as the mode argument to the Tcpdf constructor:

// Generic PDF/UA alias
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfua');

// Specific parts
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfua1'); // PDF/UA-1 (PDF 1.7)
$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfua2'); // PDF/UA-2 (PDF 2.0)

When a PDF/UA mode is active the library automatically:

• Writes a StructTreeRoot with a ParentTree that maps every page to its tagged content blocks
• Emits MarkInfo << /Marked true >> in the document catalog
• Sets /Lang (defaults to en-US when not explicitly provided)
• Forces ViewerPreferences /DisplayDocTitle true
• Maps HTML heading elements (h1-h6) to PDF structure roles H1-H6 with level-clamping to prevent skipped heading levels
• Tags text content with MCIDs and wraps each run in the appropriate structure element (P, H1-H6, Link, etc.)
• Tags <img> elements as Figure with their alt attribute written as /Alt in the structure element
• Emits ActualText entries for ligatures and special glyphs so text extraction and screen readers work correctly
• Provides Artifact marked-content helpers for non-semantic content (beginArtifact(), endArtifact(), addArtifactContent())

To provide the document language explicitly:

$pdf->setLanguageArray(['a_meta_language' => 'de-DE']);

To tag decorative or repeated content as Artifact (for example headers, footers, and page numbers):

$pid = $pdf->addPage()['pid'];

$headerOperators = $pdf->graph->getLine(10, 10, 200, 10);
$pdf->addArtifactContent($headerOperators, $pid, 'Pagination', 'Header');

$footerText = $pdf->getTextCell('Page 1', 180, 280, 20, 5);
$pdf->addArtifactContent($footerText, $pid, 'Pagination', 'Footer');

In PDF/UA mode, the built-in defaultPageContent() page-number footer is emitted as Artifact with /Type /Pagination /Subtype /Footer.

Runnable examples: examples/E015_pdfua.php through examples/E017_pdfua2.php.