FRMLS_API_OUM 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 "RMS-FRM: API LoM Output Item (Material)" 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_FRMLS_API_OUM TYPE FRMLS_API_OUM.
The FRMLS_API_OUM table consists of various fields, each holding specific information or linking keys about RMS-FRM: API LoM Output Item (Material) data available in SAP. These include MANDT (Client), RECN (RMS-FRM: Object Identifier), RECNMST (Higher-Level Object Identifier), RECNROOT (Formula Header Object)... 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. .