You open a PDF and there's a padlock in the corner, a paperclip on page two, a tiny pen on page five. None of it is labelled. Here's what those icons usually mean.
Padlocks and certificates
A padlock means the file has some kind of restriction — either an open password or permission limits. Click it and the viewer usually shows what's locked. A certificate ribbon indicates a digital signature; click for signer details and whether the file has changed since. If the ribbon is broken or red, the signature no longer matches the content. Use sign PDF for fresh signatures and password-protect PDF for locks.
Pencils, sticky notes, and highlights
Pencil icons indicate annotations — sticky notes, highlights, drawings someone added on top of the page. They're not part of the original document; they're a comment layer. You can usually click them to see who wrote what, and delete them if needed. Add your own via annotate PDF. To clean up before sending a final version, flatten the file so annotations bake into the page.
Paperclips and form fields
A paperclip means there's a file attached inside the PDF — a spreadsheet inside the report, a backup contract inside the cover letter. PDFs can carry attachments like emails do. Right-click to extract. Highlighted boxes with little arrows or checkmarks are form fields waiting for input. Click and type to fill them in.
FAQ
Why is there a red exclamation on my signature?
It usually means the signature is unverified — the signer's certificate isn't trusted by your viewer. The signature itself may still be valid; you may just need to add the signer's certificate to your trusted list.
Can I remove annotation icons before sending?
Yes — open in an editor and either delete each annotation, or flatten the file so they become permanent parts of the page (and the icons disappear).
What's the speech-bubble icon?
That's a comment or sticky note — click to read the text. Useful in collaborative reviews; less useful in a final document. Flatten or delete before sharing externally.
Icons are usually meaningful, just unlabelled. Hover, click, or open in Flint to see exactly what each one is telling you.