Revit IFC Manual is a 52-page document, which describes all of the available options for using IFC format within the Revit environment. This is definitely a handy document for everyone working with Open BIM.
This document is intended to serve as a guide for Revit users handling IFC data and providing a better understanding of the settings available in Revit, discussing the way they can influence the quality and the content of the IFC file.
The Revit IFC manual therefore sets out the basics of IFC and explains in detail how to export, link and open IFC files in Revit.
The Revit IFC Manual is available for download from the official Autodesk website (direct link). I also suggest you to check out a series of articles by Simon Moreau from BIM42 about Revit IFC exporter settings:
You may also need to update your Revit IFC exporter to the latest version: download from Sourceforge