XFA stands for XML Forms Architecture, a family of proprietary XML specifications that was suggested and developed by JetForm to enhance the processing of web forms. It can be also used in PDF files starting with the PDF 1.5 specification. The XFA specification is referenced as an external specification necessary for full application of the ISO 32000-1 specification. The XML Forms Architecture was not standardized as an ISO standard, and has been deprecated in PDF 2.0.
