Missing mass can now be specified for time history load definitions.

Missing mass and rigid body modes are reported in the output and can be selected in the post-processing mode drop-down (* for mm & + for rb)

Rigid body modes are used internally to establish relative and absolute structure displacement, particularly for structures supported on relatively weak springs.

Refer to TR.31.4 Definition of Time History Load and TR.34.2 Modal Calculation Command for additional information.