What are legacy posts? Legacy posts are threads that were made before the Jewelbox, the old forums used BBCode instead of Markdown so they may not render correctly, in addition, the old forums didn't used steam ID's where as theses do, so archived posts may not have a valid owner on them.
There is currently a small project going on where we're taking old posts and assigning them new owners assuming we can find said owner! Posts that have been assigned an owner but haven't been touched since will have a banner like the one above, and once that person edits their post, that banner will vanish.