For each PDF/A-1 validation issue we try to explain what it means and, if possible how to resolve it. For a more technical explanation of the issue we quote the related section of the ISO 19005-1 PDF/A Specification.
A document information dictionary may appear within a conforming file. If it does appear, then all of its entries that have analogous properties in predefined XMP schemas, shall also be embedded in the file in XMP form with equivalent values. Any document information dictionary entry not listed in Table 1 shall not be embedded using a predefined XMP schema property.
NOTE 1: Since a document information dictionary is allowed within a conforming file, it is possible for a single file to be both PDF/A-1 (ISO 19005-1) and PDF/X (ISO 15930-4 and ISO 15930-6 [11]) conformant.
The value of the document information dictionary entries and their analogous XMP properties shall be equivalent. For properties that map from the PDF text string type to the XMP Text type, value equivalence shall be on a character-by-character basis, independent of encoding, comparing the numeric ISO/IEC 10646-1
code points for the characters.
NOTE 2: The explicit requirement for equivalence between the values of document information dictionary entries and their analogous XMP properties has the implicit effect of providing unambiguous interpretation of that property's value.
If the dc:creator property is present in XMP metadata then it shall be represented by an ordered Text array of length one whose single entry shall consist of one or more names. Equivalence between Author and dc:creator, shall be on a character-by-character basis, independent of encoding, comparing the numeric ISO/IEC 10646-1 code points for the characters.