X_Prime returns the X coordinate of a node or the element center in grid coordinates (fig. 19). (See The Grid.)
For SUTRA and MODFLOW 6 DISV models, X_Prime is the same as X if it is used as in a default formula for a mesh. However, if it is used in a formula for an object drawn on the front view of the model, X_Prime is calculated using the angle of the cross section at the time the object was created.
Figure 20. Global and grid coordinate systems in ModelMuse.
