The PsiDimLock() function is a property function passed to PsiPivotDim().
=PsiParamDim(name, range_or_array, [PsiDimLock(elem_or_index])
The elem_or_index argument should be either the name of the locked element or its 1-based index.
Example
=PsiParamDim(“cities”, A1:A3, PsiDimLock(“LA”)) - Results in a Parametric dimension named “cities” containing three elements: NY, LA, and SF. This dimension will be locked to the “LA” dimension element.