Purpose
====

Assign loads and boundary conditions to a mechanical model.


*   For AFFE_CHAR_MECA, the assigned values do not depend on any parameters and are set
    by real values.


*   For AFFE_CHAR_MECA_C, the assigned values do not depend on any parameters and are set
    by complex values.

*   For AFFE_CHAR_MECA_F, the values assigned are a function of one or more parameters in
    the set {INST, X, Y, Z, Z, Z, Z, Z, Z, Z}.