BAPI_WBS_MILESTONE_UPD 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 Structure Milestones under WBS Elements (Update Fields)" 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_BAPI_WBS_MILESTONE_UPD TYPE BAPI_WBS_MILESTONE_UPD.
The BAPI_WBS_MILESTONE_UPD table consists of various fields, each holding specific information or linking keys about BAPI Structure Milestones under WBS Elements (Update Fields) data available in SAP. These include WBS_ELEMENT (Updated information in related user data field), MILESTONE_USAGE (Updated information in related user data field), DESCRIPTION (Updated information in related user data field), SCHED_MILESTONE_DATE_BASIC (Updated information in related user data field)... 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. .