CNVT_CONVERSION_MESSAGE 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 "Messages From Conversion" 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_CNVT_CONVERSION_MESSAGE TYPE CNVT_CONVERSION_MESSAGE.
The CNVT_CONVERSION_MESSAGE table consists of various fields, each holding specific information or linking keys about Messages From Conversion data available in SAP. These include TYPE (Message type: S Success, E Error, W Warning, I Info, A Abort), ID (Message Class), NUMBER (Message Number), MESSAGE (Message 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. .