The FORCE module forms the load force vector for external load cases. This module is of no use for seismic soil-structure interaction problems. The loads may correspond to impact forces, rotating machinery, or simple unit forces to be used to determine the impedance of a flexible foundation. The results are stored in File 9. When foundation flexibility is not a significant concern the use of the direct impedance evaluation option included in the ANALYS module active for seismic option is clearly more efficient.