ATPCA 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 "ATP Controller: Control Parameters" 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_ATPCA TYPE ATPCA.
The ATPCA table consists of various fields, each holding specific information or linking keys about ATP Controller: Control Parameters data available in SAP. These include ANWDG (ATP Server: Calling application), ANWDG2 (ATP Server: Calling application), ANWDG_ORIG (ATP Server: Calling application), OKDBD (ATP Server: 'Check without customer requirements' flag)... 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. .