RSDDG_S_PARAMETER 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 "Description of a Parameter of Data Target" 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_RSDDG_S_PARAMETER TYPE RSDDG_S_PARAMETER.
The RSDDG_S_PARAMETER table consists of various fields, each holding specific information or linking keys about Description of a Parameter of Data Target data available in SAP. These include TYPE (Type of an InfoObject), DATA_TYPE (Data Type of a Parameter for a Data Access Service), DATA_LENGTH (Length of a Parameter (for CHARACTER data type)), MANDATORY (Parameter is Mandatory)... 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. .