Period to date functions for time intelligence functionality

A system for extending a Time Intelligence language to provide support for period-to-date functions and for generating member sets in response to data queries is provided. The system may apply member aggregation functions and queries across a plurality of heterogeneous data sources. Each data source is aligned to a reference dimension and is said to organize data according to at least one level of granularity. In some embodiments, a member aggregation function specifies a period (e.g., year, quarter, month) and retrieves data from a data source starting with the current specified period and ending with the most recently completed period equal to the granularity of the data source. The system may allow a user to further customize a member aggregation function by specifying a granularity, a period offset, or a granularity end offset. Additionally, the system may generate a caption to display in association with the retrieved data.