[numlock86]

What do you mean? This is pretty common here. Nevertheless it should be included in the title if that is what you are getting at.

[romaniitedomum]

Yes, putting PDF into the title is considered polite.

[pushrax]

On the other hand, if you don't want to open pdfs by accident, use "Always Ask" .. https://support.mozilla.org/en-US/kb/disable-built-pdf-viewe...