COINDEX is an SAP Structure so does not store data like a database table does but can be used to process "Structure With Field Analogous to Sy-Tabix" 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_COINDEX TYPE COINDEX .
Below is the documentation avaialable and full details of the fields which make up this Structure.
Delivery Class: A - Application table containing master and transaction data
Display/Maintenance via SM30: Yes but with Restrictions
Enhancement category i: Can be enhanced (character-type or numeric)
See here for more information about this and other SAP enhancement categories
|Data Type||length (Decimals)||Check table||Description||Conversion Routine|
|INDEX||TABIX_D||INT4||10||Field defined as in SY-TABIX|