The Customer dataset contains multiple segmentations. There is a corporate level segmentations which is standardized across all GBUs and is primarily used for cross-GBU reporting. There are also GBU-specific segmentations which are used for more day-to-day operations and analysis within the GBUs and which are more directly related to the GBU's products and applications.
For customers which are served by more than 1 GBU, this means in practice they have 1 corporate segmentation value and up to 5 GBU-specific segmentation values.
Reference:
At Group level, GBU segmentations are consolidating into one Group segmentation, mainly for performance monitoring purpose, according to 2 elements:
Customer segmentation is being defined at GBU level, allocating accounts to one of the 5 following segments:
(For details on the GBU customer segmentation assignment look into the slides 12 and 13 in the slides above)