FMDT_RO_KEY 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 "key fields for Rental object" 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_FMDT_RO_KEY TYPE FMDT_RO_KEY.
The FMDT_RO_KEY table consists of various fields, each holding specific information or linking keys about key fields for Rental object data available in SAP. These include BUSINESS_ENTITY (Site Number), RENTAL_UNIT (Number of Rental Unit), POSTING_DATE (Posting Date in the Document)... 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. .