# Step 2: Adjust for calculated members and named sets

If your Mondrian schema defines calculated members or named sets that reference MDX members without the dimension prefix, then you must set `mondrian.olap.elements.NeedDimensionPrefix` to `false` in your `mondrian.properties` file. Under all other conditions you would set this property to `true` because it increases Mondrian performance, as well as the readability of the schema XML file.