Data Model 4.1.4 - Consistency issues

The first sentence of 4.1.4 reads, "When a data model fragment is created 
from the PSVI a document information item is mapped to a Document Node."

This sentence seems to me to potentially create consistency problems, 
particulary when read with the final sentences of 4, "A tree whose root node 
is a document node is referred to as a document.  A tree whose root node is 
some other kind of node is referred to as a fragment."

If, as is suggested in 4, a fragment has a root node not of kind "document 
node" then 4.1.4 seems inconsistent with this. Perhaps the way to remedy the 
seeming inconsistency is to use a phrase other than "data model fragment" in 
4.1.4?

Andrew Watt