Please find the documentation for the Reference View 1,2, based on IFC4 ADD2 TC1 here:
http://standards.buildingsmart.org/MVD/RELEASE/IFC4/ADD2_TC1/RV1_2/HTML/
For those who wish to have a local version, please download the ZIP file with this link:
http://standards.buildingsmart.org/MVD/RELEASE/IFC4/ADD2_TC1/RV1_2/ifc4-add2-tc1-rv-12_20181221_final.zip
The buildingSMART International technical website, buildingsmart-tech.org, will be edited to reflect this as well.