Now that you have opened a document, here is brief explanation of what you are looking at.
An iTWO RIB cx Document is broken down into 4 tabs.
...
It also includes the comment history. The comment history is all the replies and comments added by the users on your iTWO RIB cx Project about this document overtime.
...
The related tab give you access to the documents that are linked to the document you are on.
On iTWO cxRIB cx, these documents are displayed in the Linked section.
...