What is XFA?
Definition
XFA (XML Forms Architecture) is Adobe LiveCycle Designer's format for PDF forms: the fields, layout rules and calculations live in an XML template embedded in the PDF, separate from the AcroForm fields most PDF forms use.
Static vs. dynamic
A static XFA form also carries a visible page with ordinary form boxes, so it can be viewed and filled like any other PDF. A dynamic XFA form has no visible page outside Adobe software: its layout is computed on open, so only Adobe Reader or Acrobat can render it.
How Emboss fills an XFA form
Emboss reads an XFA form's template directly and writes values into its datasets, the same data Adobe Reader and Acrobat display. A dynamic form whose layout flows or repeats rows is refused rather than guessed at. See [XFA forms](/docs/xfa-forms) for the full behaviour.