Signatures & forms
AcroForms vs XFA forms
PDF has two form technologies. Knowing the difference explains why some forms open fine everywhere and others show "please use Adobe Reader."
AcroForms
AcroForms are the original, widely supported PDF form fields. They open and fill in virtually every reader, on every platform.
XFA
XFA forms are an XML-based Adobe technology that many readers do not support and which has been deprecated in the PDF 2.0 standard. They cause the dreaded compatibility warnings.
Which to build
Always build AcroForms for portability. They are the reliable, standard choice.
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