qpdf: selecting --keep-open-files=y
qpdf: fxo-red.pdf: checking for shared resources
qpdf: no shared resources found
qpdf: removing unreferenced pages from primary input
qpdf: adding pages from fxo-red.pdf
qpdf: processing underlay/overlay
  page 1
    overlay 1
    overlay 2
    overlay 3
    overlay 4
qpdf: wrote file a.pdf
