/T — author / title. Empty when absent.
/Subj — subject. Empty when absent.
/CreationDate — raw PDF date (D:YYYYMMDD…). Empty when absent.
/M — raw PDF modification date. Empty when absent.
/Name — stamp name (e.g. "Approved"). Empty when absent.
/CA non-stroking opacity, 0..=1 (1 = opaque).
/C normalised to RGB 0..=1 ([] when no colour).
/QuadPoints (8 values per quad) for text-markup annotations.
/InkList — one inner array per freehand stroke (x y x y …).
Link external URI (/A /URI). Empty when internal/absent.
Link internal destination page (1-based); 0 when external/absent.
A markup annotation (rect corners in PDF user space, origin bottom-left). Carries the common metadata plus the type-specific geometry a host editor needs: text-markup
quadPoints, freehandinkList,stampname, and the link target (linkUri/linkPage).