How to attach a file to a comment?

Drupal, the software that powers iMechanica, treats comments very differently from a blog entry.  You cannot attach a file to a comment directly. 

One way to link to a file in the comment is to first write a new blog entry, where you can upload the file. The blog entry and the uploaded file have distinct URLs. In your comment, you can choose to hyperlink to your blog entry, or to the uploaded file.