PROJ_BAPI 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 "BAPI fields: PROJ" 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_PROJ_BAPI TYPE PROJ_BAPI.
The PROJ_BAPI table consists of various fields, each holding specific information or linking keys about BAPI fields: PROJ data available in SAP. These include POST1 (PS: Short description (1st text line)), KIMSK (Selection mask for WBS element short IDs), STSPD (Status profile for project definition), STSPR (Status profile for WBS element)... 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. .