CMP_CUST_FIELDS_S is a standard SAP Structure so does not store data like a database table does. It can be used to define the fields of other actual tables or to process "Include Customer-Specific Selection Criteria (Mass Comp.)" Information within sap ABAP programs. This is done by declaring abap internal tables, work areas or database tables based on this Structure. These can then be used to store and process the required data appropriately. i.e. DATA: wa_CMP_CUST_FIELDS_S TYPE CMP_CUST_FIELDS_S.
The CMP_CUST_FIELDS_S table consists of various fields, each holding specific information or linking keys about Include Customer-Specific Selection Criteria (Mass Comp.) data available in SAP. These include MANDT (Client), VBELN (Billing Document), FKART (Billing Type), FKTYP (Billing category)... See below for full list along with technical details, documentation, text table, check tables, foreign key relationships, conversion routines, relevant tcodes and example ABAP select code etc. .