IPXC_AcroForm::Root Property
From PDF XChange PDF SDK
Returns fake root field that contains all top level fields of the form as children. The Root field is designed to unify the structure of the form fields as a tree with one common root. The root field has no value, has no PDF object associated with it, etc.
Syntax
HRESULT get_Root([out, retval] IPXC_FormField** ppRoot);