id names an EXISTING row, omit it for a new box. Callers must send back the ids they read: coordinates.id keys sub-field answers, so a reinsert orphans them.
id
coordinates.id
Optional
1-based.
NULL = the annotation's parent box; non-NULL = a sub-field prompt (v1 semantics).
PDF points, top-left origin — persisted as plain numeric strings (v1 read-compat).
idnames an EXISTING row, omit it for a new box. Callers must send back the ids they read:coordinates.idkeys sub-field answers, so a reinsert orphans them.