Acroforms (also known as Acrobat forms) is a mechanism for adding forms to the PDF file format.
Acroforms lets you use objects (text boxes, radiobuttons, etc.) and some JavaScript code. Maintains the values of the fields in external files, in which the key-value pair is stored. The external file may use different formats such as ASCII, FDF or XFDF files.
It was introduced in version 1.2 of the PDF format. In version 1.5, Adobe added the proprietary format for XFA forms. Both formats coexist today.
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