ValidatePdfR method

ValidatePdfR walks the open document looking for the file-format markers defined by ISO 23504-1:2020:

• The %PDF-raster-x.y version-identification comment near the end of the file (§5).
• A header line of the form %PDF-1.4, %PDF-1.5, %PDF-1.6, or %PDF-1.7 (§6.2.2) for unencrypted files, or %PDF-2.0 (§6.2.3) for encrypted files.
• The absence of object streams (/Type /ObjStm — §6.2.4).
• Catalog dictionary compliance with the §6.3 white list (Version / ViewerPreferences / PageLayout / PageMode / AcroForm / Metadata; everything else triggers pvriProhibitedCatalogEntry).
• Document Information Dictionary compliance with the §6.4.3 white list (Creator / Producer / CreationDate / ModDate; Title / Author / Subject / Keywords / Trapped trigger pvriProhibitedInfoEntry).
• An XMP metadata stream in the catalog (§6.4).
• A trailer /ID array.

The result is a TPdfRValidationResult record:

• Conformance — prc1 (PDF/R-1 marker found), prcNone (no marker), or prcUnknown (parse failed or document inactive).
• Issues — a TPdfRValidationIssues set with zero or more values: pvriMissingVersionMarker, pvriBadHeader, pvriObjStmPresent, pvriProhibitedCatalogEntry, pvriProhibitedInfoEntry, pvriInfoXmpMismatch, pvriMissingXmpMetadata, pvriMissingTrailerId.
• IsCompliant — returns True when Conformance is a real PDF/R level and Issues is empty

ValidatePdfR is a read-only file-format inspection. PDF/R-1 compliance has strict structural requirements that this method does not check — per-page Contents structure, MediaBox form, allowed filters, generation-zero indirect references, strip layout. Pair with a TWAIN Working Group PDF/R validator for those content-level checks.

• The version marker check looks for %PDF-raster- as a substring anywhere in the file. ISO 23504-1 §5 specifies the marker is placed between the trailer dictionary and startxref, but the validator accepts other locations to remain forgiving of slightly non-standard generators.
• Calling ValidatePdfR on an inactive document returns a record with Conformance = prcUnknown and an empty Issues set.
• Encryption is permitted by §6.2.3 (with a %PDF-2.0 header), so the validator does NOT flag the trailer /Encrypt key as a non-conformance. Source PDFs encrypted under PDF 1.x would still fail because of the header check.