HEADER_CUST 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 "Structure for user exit PPCO0006" 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_HEADER_CUST TYPE HEADER_CUST.
The HEADER_CUST table consists of various fields, each holding specific information or linking keys about Structure for user exit PPCO0006 data available in SAP. These include APRIO (Order priority), CY_SEQNR (Seq. number order), GSBER (Business Area), FUNC_AREA (Functional Area)... 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. .