COEPL_ONLY 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 "Non-key fields, only in COEPL (INCLUDE structure)" 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_COEPL_ONLY TYPE COEPL_ONLY.
The COEPL_ONLY table consists of various fields, each holding specific information or linking keys about Non-key fields, only in COEPL (INCLUDE structure) data available in SAP. These include MEINH (Activity unit), LSTBTR (Activity Quantity), MEINB (Posted Activity Unit), LSBBTR (Activity quantity in document)... 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. .