Work on the structural properties of coal and rocks was confined to preparation of the final report Structural Characteristics of Coal. Continued effort was made to upgrade and improve the longwall simulation. As part of the effort, a fresh look is being taken at the method of calculating support loads and in particular the method of determining whether a roof will form a cantilever behind the chock line. The system, based purely on strata strength, density, modulus, and thickness consideration, appears limited in scope as it ignores the rock mass properties. Therefore, a rock mass classification method of characterizing the roof strata is being investigated. In particular this would allow evaluation of the joint systems in addition to other structural properties and should provide a more realistic determination of support load. The major problem with the approach is seen to be the difficulty in obtaining adequate rock mass data from exploration boreholes. This problem is also to be investigated particularly in the light of new down-the-hole geothermal investigation devices. Work continued on the final report of the roof truss portion of the work. The report includes the theory, modeling method, experimental and field data, and the analysis and correlation of the above, in addition to recommendations concerning efficient installation and usage of roof trusses.