
The Field Member Captions dialog is most commonly used to rename dimensions.

In this example, the Segment1 dimension has been renamed "Account". This causes Segment1 to be relabelled as "Account" in every control and dialog across the entire product - as well as in the report itself.

In this example, division 10 (Sales), has been renamed to "Domestic Sales". Whenever division 10 is encountered in the data returned for the report, it will now be captioned "Domestic Sales". It will also be seen as Domestic Sales when using the selection dialogs.
These are not global changes and only apply to the current report.
Captions can be rapidly duplicated or copied to other reports using the "Cut / Copy / Paste" buttons.
In addition, Captions can be stored in the library and other reports can subscribe to the same definitions. Find out more about the library feature here.
Captions can be re-ordered using the arrow buttons. This has no impact on the execution of the report but allows them to be organised into manageable groups.