The drill down and drill up capabilities on the date and date time fields is a new navigational enhancement. Clicking "+" expands the hierarchy into year, quarter, month, weeks, days, hour, minute, seconds. Clicking "-" collapses the hierarchy. This streamlined user interaction is supported in Columns, Rows, and Chart Properties Decks.
Applicable only to Primary Date Dimensions in the Columns, Rows, Break, and Label Decks
Visual Analytics expands the discreet date dimension to its lowest level.
Primary continuous date dimensions do not support date and date and time hierarchy.
Applicable only to Primary Date Dimensions in the Colors and Shape Decks and Secondary Date Dimensions
Clicking "+" changes the same date field level to a lower level hierarchy. On reaching the lowest level of the date dimension, when you click ‘+’, Visual Analytics starts the date hierarchy from the highest date dimension.