The BleedBox defines the region to which the contents of the
page shall be clipped when rendered in a production
These boundaries are always defined directly on the Page object.
If no property has been defined then this property will be null and
the effective value is assumed to be that of the CropBox.
Note that, as with all objects in this namespace, this property
is measured in points in the native PDF coordinate space. It is
unaffected by the Doc.Units or