Character tags have now been added back to 2009. Everything before that remains untagged. If you want to be responsible for backtagging all of your character's posts, that would be a huge help. Adding content markers is optional and can come later.
The open post (or open thread) tag is to be used for big posts like TRAVEL or WATERPARK. Just tag them open thread and add your character's name if you participated. Other people can go back through open threads and tag accordingly.