Message type: E = Error
Message class:  W8 - Workflow: Expressions, data flow 
Message number: 188
Message text: Element & is only intended for data export
The container definition for this step flags the element &V1&
for data export. Therefore, the element cannot be assigned data at the
import interface for this step.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
Error message extract from SAP system. Copyright SAP SE.
SAP Error Message: W8188 Element & is only intended for data export
Cause: This warning message occurs when you try to use or process a particular element (field or structure) in a context where it is not intended to be used. Specifically, the element flagged by this message is designed only for data export purposes and should not be used for data input, modification, or other processing activities. In other words, the element is defined in the system as an output-only field, typically used to export data from SAP to external systems or reports, and is not meant to be updated or manipulated within the SAP system. When does it typically occur? When you try to input or modify data in a field that is marked as export-only. When customizing or enhancing data interfaces (e.g., IDocs, BAPIs, or data transfer programs) and mistakenly using export-only elements as input. During data migration or integration scenarios where the data flow
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