Four new extraction research documents covering PDF portfolio and
attachment enumeration (ZUGFeRD, PDF/A-3 AFRelationship), incremental
update structure and xref chaining, PDF/UA tagged PDF deep dive with
all 36 structure types and MCID mechanics, and JavaScript/AcroForm/XFA
field extraction without script execution.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
