E3CLASS 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 "OO classes (classes, materials, tables, functions)" 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_E3CLASS TYPE E3CLASS.
The E3CLASS table consists of various fields, each holding specific information or linking keys about OO classes (classes, materials, tables, functions) data available in SAP. These include OBJID (Internal counter for objects in an SCE knowledge base), OBJNAME (Name of OO class), OBJTYPE (Type of OO Class in SCE), CLASSTYPE (Class type)... 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. .