This article will help you to:
Understand what a cross-API dimension is
Learn how to use them
A cross-API Dimension is a universal Dimension which can be used across multiple Data Sources where applicable.
At the moment, these are the existing cross-API Dimensions:
Date
Week
Month
Year
Campaign
Source
Medium
Source/Medium
Cross-API Dimension can be found along with other Dimensions:
Cross-API Dimension date format
The format for the cross-API date Dimension is YYYY-MM-DD.
Edge cases
Campaign, Source, Medium, and Source/Medium, only apply to Google Analytics and Google MCF.