I just want to start by repeating what I said in the alert that I sent to you when I moved your thread: The "General XenForo discussion and feedback" forum is not for support related queries. I have moved this thread, again.
The content inside an ATTACH bb code is the attachment ID.
Except that the ATTACH documentation appears to be incomplete. For instance type and alt parameters are not documented there. For attachments which are not images is there a way to change the default link text which simply says "View attachment filename"?