- 1). Open Notepad and create the contents of your DAT file.
- 2). Click "Save As" from the "File" menu.
- 3). Select "All Files" from the "Save as type" box.
- 4). Type the name of the file followed by the extension ".dat" (for example, type form.dat") in the "File name" box.
- 5). Click "Save."
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