API_PNRL_DOWN_STRUC 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 "Node Relationships" 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_API_PNRL_DOWN_STRUC TYPE API_PNRL_DOWN_STRUC.
The API_PNRL_DOWN_STRUC table consists of various fields, each holding specific information or linking keys about Node Relationships data available in SAP. These include ALTNUM1 (Alternative of an iPPE Node), CLINT1 (Internal Class Number), PNAME1 (iPPE Node Description), CLASS1 (Class 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. .