E3ACA2C 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 "Posting in FI/CO from MM: Currencies" 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_E3ACA2C TYPE E3ACA2C.
The E3ACA2C table consists of various fields, each holding specific information or linking keys about Posting in FI/CO from MM: Currencies data available in SAP. These include WAERS (Currency Key), WRBTR (Amount or tax amount in the currency of the currency types), BUALT (Amount posted in alternative price control)... 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. .