Should null predicate be considered part of the alignment?

[cloudygoose]

Hi, thanks a lot of sharing this work!
I'm a bit confused about the null predicates. And there seem to be many of them in the dataset.
What does it mean? Does it mean only the subject / object of this triple is aligned?
Or the whole triple is aligned (with the document), but due to some reason the surface-form can not be located?
And are they also tested in for accuracy in the report?

Thanks!