GRFN_S_API_CUSTOMFIELD_MDATA 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 "CDF FIeld Metadata" 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_API_CUSTOMFIELD_MDATA TYPE GRFN_S_API_CUSTOMFIELD_MDATA.
The GRFN_S_API_CUSTOMFIELD_MDATA table consists of various fields, each holding specific information or linking keys about CDF FIeld Metadata data available in SAP. These include FIELDNAME (Name of the Custom Field), FIELDLABEL (CDF Label), MULTI_VALUE (New Input Values), REGULATION_VALUE (New Input Values)... 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. .