What is the scope of a data class? According to my understanding it's scope is global. Can call any data class in work class using page reference. So what is the need of different data layers like Organization level data layer and implementation level data layer?
Data Class is not only to create Data Types or Data Pages, but we also create other rules in Data Class (for example: activities, flowactions, flows, sections, etc.). So the different data layers like organization, implementation, etc. are to define the scope of these other rules.
For example when you use split for each, you provide a Page list property and the flow name. This flow is created in the Data Class. So the scope of this flow will be defined based the layer in which you have created the flow.