SDTEXT_TREESITEM 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 "Word Processing: Node Structure" 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_SDTEXT_TREESITEM TYPE SDTEXT_TREESITEM.
The SDTEXT_TREESITEM table consists of various fields, each holding specific information or linking keys about Word Processing: Node Structure data available in SAP. These include NODE_KEY (Tree Control: Node Key), ITEM_NAME (Tree Control: Column Name / Item Name), CLASS (Natural Number), FONT (Natural Number)... 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. .