GRFN_S_REP_FIELDS 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 "Reports: Special fields" 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_GRFN_S_REP_FIELDS TYPE GRFN_S_REP_FIELDS.
The GRFN_S_REP_FIELDS table consists of various fields, each holding specific information or linking keys about Reports: Special fields data available in SAP. These include RESP_USER_T (Owner), TIMEFRAME (Timeframe), TF_YEAR (Timeframe Year)... 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. .