LOG_ITEM 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 "Forecast Cost Detail List" 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_LOG_ITEM TYPE LOG_ITEM.
The LOG_ITEM table consists of various fields, each holding specific information or linking keys about Forecast Cost Detail List data available in SAP. These include PERIO (Period), GJAHR (Fiscal Year), KSTAR (Cost Element), PLANKST (Total Value in Controlling Area Currency)... 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. .