PDF/A-2u (ISO 19005-2, level U, Unicode): PDF/A-2b, and every glyph shown maps to a Unicode value, through the font's
ToUnicode CMap or the other means the standard allows (a standard encoding, glyph names from the Adobe Glyph List, a
predefined CJK character collection), never to U+0000, U+FEFF or U+FFFE: the text can be searched and extracted.
PdfA2u = 2
ISO 19005-2, 6.2.11.7.2 (veraPDF PDF/A-2U validation profile, rules 6.2.11.7.2-1 and -2).