You can select DTS substitution variables.
Substitution variables are predefined placeholders, used for frequently changing information, identified by variable names, and having temporary values that define data type. When substitution variables are used, temporary values are replaced by current values. Substitution variables are stored at the database level in Analytic Services.
To define a DTS selection:
The Dynamic Time Series dialog box is displayed, listing DTS definitions as option buttons and substitution variables in a list.
Select the Substitution Variables tab, and then select a substitution variable.
Select the Members tab, and then select a member to represent the date in the X-to-date definition.