FRMLS_IOT_SRC 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: IO Tab for Dialogs with Compositions" 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_IOT_SRC TYPE FRMLS_IOT_SRC.
The FRMLS_IOT_SRC table consists of various fields, each holding specific information or linking keys about RMS-FRM: IO Tab for Dialogs with Compositions data available in SAP. These include MARKFLG (Row Is Selected), SELEFLG (Step Loop Line Selected), LINENO (General Auxiliary Counter), LINEMOD (Processing status or mode of a record/step loop line)... 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. .