Concept of merging the financial dimensions of existing values with new values

Hi All, Most of the people still does know the concept of merging the financial dimensions of existing values to new values on most of the line base or transaction base tables. 

 1) Taking an example of SalesLine Table where there is a method called mergeDimension.

 2) we need to pass the existing defaultDimenion of saleline record in the 1st parameter and 

 3) pass the new defaultdimension value in the 2nd parameter of the method 

4)  Or passing individual like ProjTable defaultDimension and Item defaultDimension into salesLine to merge as Single financial Dimension of salesline. 

 Eg: