whether the target's own record, in the same document, declares the inverse of this
reference. A NodeSet2 file declares most references from both ends, and a back reference is
only needed where it does not; a producer that has seen the whole document (the image) sets
this so the loader propagates the few that need it instead of checking every one. Left
undefined by a streaming producer: the loader then checks at the end of the load.
whether the target's own record, in the same document, declares the inverse of this reference. A NodeSet2 file declares most references from both ends, and a back reference is only needed where it does not; a producer that has seen the whole document (the image) sets this so the loader propagates the few that need it instead of checking every one. Left undefined by a streaming producer: the loader then checks at the end of the load.