FMHIE_S_NODE_STRING 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 "Hierarchy structure with character fields (for traversal)" 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_FMHIE_S_NODE_STRING TYPE FMHIE_S_NODE_STRING.
The FMHIE_S_NODE_STRING table consists of various fields, each holding specific information or linking keys about Hierarchy structure with character fields (for traversal) data available in SAP. These include ROOT (Node ID for traversal (character based)), PARENT (Node ID for traversal (character based)), NEXT_SIBLING (Node ID for traversal (character based)), CHILD (Node ID for traversal (character based))... 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. .