Additional post data is a function grantable to users but does not come default, it is used for custom threads like polls, templates, guild tools, etc. If you don't have it don't panic! And if you think you require it, contact me!
Additional post data comes in the forum of a text box where you must enter in your blocks of data + variables on a per line basis.
For example, setting a thread to have a sidebar is done as so.
thread_sidebar = "1"
thread_sidebar = "1" ;Allows the thread to have a sidebar, this is required with most additional tools; table_of_contents ="1" ;Adds in a table of contents section, requires thread_sidebar to be set to 1, uses Markdown headers as chapters; map_feedback = "1" ;Adds in a feedback table of collected feedback from the map feedback maintenance page. map_name = "map_name" ;The exact map name, if it exists in the feedback list, it'll show up here.
This list will be periodically updated as more additional thread tools are made available! Feel free to post suggestions below.