T156X : T156X is a SAP standard transparent table used for storing Trans./Event Key Modification related data in SAP. It comes under the package MB
2206980 : Material Inventory Managment: change of data model in S/4HANA
1.2.2 : Fields representing a customer defined stock type or quantity/value to be aggregated
If own stock types or a dimension which needs to be aggregated have been introduced by the customer then the view stack of the CDS view assigned to the table with the additional stock type needs to be modified. Right now, there is no technology support for modification free enhancement. If the stock type has not been introduced by new entries or enhancements in the tables T156x (T156, T156SY, T156M, T156F) – which controls in the core functionality the mapping between a posting and a stock type – then the process logic needs to be adapted.