Hello,
Enabling the pdfa3 option (with the macro included in the package) with phpdocx 14 and newer releases, uses PDF/A-3b (PDF/A, ISO 19005) included in LibreOffice. This adds XML information to the PDF output such as:
<</Type/Metadata/Subtype/XML/Length 5350>>
stream
<?xpacket begin="" id="W5M0MpCehiHzreSzNTczkc9d"?>
<x:xmpmeta xmlns:x="adobe:ns:meta/">
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<rdf:Description rdf:about="" xmlns:pdfaid="http://www.aiim.org/pdfa/ns/id/">
<pdfaid:part>3</pdfaid:part>
<pdfaid:conformance>B</pdfaid:conformance>
</rdf:Description>
<rdf:Description rdf:about="" xmlns:dc="http://purl.org/dc/elements/1.1/">
<dc:format>application/pdf</dc:format>
<dc:creator>
<rdf:Seq>
<rdf:li>dynadocx</rdf:li>
</rdf:Seq>
</dc:creator>
</rdf:Description>
<rdf:Description rdf:about="" xmlns:pdf="http://ns.adobe.com/pdf/1.3/">
<pdf:Producer>LibreOffice 24.2</pdf:Producer>
<pdf:PDFVersion>1.7</pdf:PDFVersion>
</rdf:Description>
<rdf:Description rdf:about="" xmlns:xmp="http://ns.adobe.com/xap/1.0/">
<xmp:CreatorTool>Writer</xmp:CreatorTool>
<xmp:CreateDate>2023-10-17T13:08:00+02:00</xmp:CreateDate>
<xmp:ModifyDate>2023-10-17T13:08:00+02:00</xmp:ModifyDate>
<xmp:MetadataDate>2023-10-17T13:08:00+02:00</xmp:MetadataDate>
</rdf:Description>
</rdf:RDF>
</x:xmpmeta>
Also note that all macros can be customized when being added to your installation if you want to add extra settings when using it.
Regards.