Currently we support use cases for Non Additive measures and Additive measures for Non additive measures we create non aggregated measures in the advanced calculation editor. However, there is a greyed line for certain examples of semi additive measures. You can create some measures that are "Semi" additive like via advanced calculations, but this is an area that we are looking into currently. It would be of great help to me and the product itself if you could outline some use cases that way we can make sure to cover what you are looking for in calculations. It is always possible that we could find a way to nail your use case now as well depending on the business problem you are trying to solve.
Regards,
Ted Werner