SDLSDSH 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 "Transfer Structure for Release Header" 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_SDLSDSH TYPE SDLSDSH.
The SDLSDSH table consists of various fields, each holding specific information or linking keys about Transfer Structure for Release Header data available in SAP. These include DOC_NUMBER (Document Number (Purchasing/Sales...)), ITM_NUMBER (Item Number of Document (Purchasing, Sales...)), COUNTER (Internal Counter), SCOID (Generic Data Element for GUID Fields (C22))... 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. .