Explanation/Reference:
* In order to calculate period-to-date values dynamically, you need to use a Dynamic Time Series member for a period on the dimension tagged as time.
* Use built in Dynamic Time series calculations for period - to - date calculations such as YTD, QTD, & MTD accumulations. DTScalculations are on the fly and require time related dimension to be tagged as Time.
* * You do not create the Dynamic Time Series member directly in the database outline. Instead, you enable a predefined DynamicTime Series member and associate it with an appropriate generation number.
* Dynamic Time Series members are not displayed as members in the database outline. Instead, Essbase lists the currently active Dynamic Time Series members in a comment on the time dimension.
Reference: Basics of Hyperion Essbase