COSELECT 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 "Interface Structure for Selection Criteria" 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_COSELECT TYPE COSELECT.
The COSELECT table consists of various fields, each holding specific information or linking keys about Interface Structure for Selection Criteria data available in SAP. These include SIGN (Selection criteria: SIGN), OPTION (Selection criteria: OPTION), LOW (Selection criteria: From value), HIGH (Selection criteria: To value)... 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. .