The brief was read, edit, and sign, at the very least. Signing a government PDF means filling it in first, so forms are the half of “sign” that had to land before the signature itself.
What it does
Every common field type fills through the rendering engine: text, checkbox, radio, dropdown, and list. The encrypted forms the IRS and USCIS publish, which many free tools open read-only or not at all, fill and save. A save appends only the objects that changed, so the rest of the file is byte for byte what it was, and a prompt asks whether to keep the form editable or flatten it into fixed page content.
Answers are learnt on save, so the next form with a name or address field already has them. They are stored encrypted under the Windows account’s own key, and a sensitive-field filter refuses to remember anything that looks like a social security, account, card, or ID number.
What review caught
The first version of Flatten rendered the answers into the page and removed the fields, but because a save appends to the file, the typed answers were still sitting in plaintext in the earlier revision underneath. A flattened W-9 would have carried its contents in the clear. Flatten is now a full rewrite of the file, and a test scans the output for remnants of every answer.
Minor decisions, made alone
The owner’s standing instruction is the pull quote. Two calls were made under it without asking: Keep editable is the default on save, and the nine-digit extended ZIP code is exempted from the digit filter so addresses are remembered whole. Signatures, the second half of the third verb, are the next slice.