Just as Mara Zebest and others have shown for the White House Long Form Birth Certificate, the Xerox 7655 scan also contains layers and a clipping path.
Zebest: In addition to the nine sub-layer objects, a clipping path is at the top of the sub-layer list. The clipping path groups all the remaining sub-layers below.
Mara also may want to revise her claim that:
Zebest: At the risk of sounding like a broken record, this is not normal, unless the document has been compiled digitally.
Technically speaking, she is correct, the document was compiled digitally by combining foreground layers with a background layer, but it was all done by the software.