FMBGADH 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 "Screen Structure: PCO Input Tax Adjustment" 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_FMBGADH TYPE FMBGADH.
The FMBGADH table consists of various fields, each holding specific information or linking keys about Screen Structure: PCO Input Tax Adjustment data available in SAP. These include BELNR (Accounting Document Number), BUDAT (Posting Date in the Document), BLDAT (Document Date in Document), BKTXT (Document Header Text)... 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. .