There have been several examples of documents, maps and other items that pertain to the D'ni civilization that have not been released to the public explorer community. These documents however have either been discovered by or given to select members within said community.
These documents often shed light on previously unknown aspects (to the explorer community that is) of D'ni culture and its Ages.
Cavern Map 01
Cavern Map 01 is a map complied that shows an overview of the entire D'ni Cavern. It shows the locations of K'veer, Katha Island, The Cult Colonys, Maintainer Island and various city expansion areas.
Cavern Map 02
Cavern Map 02 is more focused on Ae'gura and The City Proper. It shows the location of various Guild structures, religious temples as well as the Kerath'en District. It also has date notations of when the various areas were established.
In mid 2004 the first few explorers started to take what is commonly known as "The Path of the Shell". A secondary journey set forth by Yeesha to further teach the explorer community of the D'ni history.
One such explorer was Ryan Miller of the company CyanWorlds who have worked closely with the DRC in the past. Ryan penned a document that has since been designated by The Third Path as the RMPOT5:04 Document as a sort of walk-through for other select explorers to follow. The document heavily referenced information discovered by the DRC that for the most part had not been made public knowledge, with a lot of references to Guild Master Kadish and his history.
The document has never been made public and it is unknown how many people actually have copies of it.