E3PRTDP 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 "Assgmts of Classic Dependencies to Parts of a Decomposition" 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_E3PRTDP TYPE E3PRTDP.
The E3PRTDP table consists of various fields, each holding specific information or linking keys about Assgmts of Classic Dependencies to Parts of a Decomposition data available in SAP. These include DECOMPID (BOM number), POSID (Internal counter for objects in an SCE knowledge base), DEPID (Internal counter for objects in an SCE knowledge base), POSNR (Item 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. .