Info structure: use of user exits is not supported

What causes this issue?

The transfer to Demand Management using user exits requires that
the info structure being used contain a characteristic that has the
domain 'PS_POSNR'.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Use an info structure with a characteristic that has the domain
'PS_POSNR'.

Error message extract from SAP system. Copyright SAP SE.