I have a PDF document that when examining its metadata has this object:
2 0 obj
<< /Type /Pages
/Count 4
/Kids [3 0 R 22 0 R 25 0 R 28 0 R]
/DefaultValue (GykqNSk/dAoeHHo8NSh6dBQfDnpobnRodGo=)
>>
endobj
Appare…... Pages, Annotations, etc. It also leaves/adds...