This is a function in Tcl's C interface. It returns a reference to a Tcl_Obj that holds the empty string. The reference will have a reference-count of zero; it is up to the caller to increment the reference count via Tcl_IncrRefCount (or delegate that to one of the reference-retaining operations in Tcl's C interface) or to ensure its destruction via Tcl_DecrRefCount.

The signature of this function should be treated as if it was:

extern Tcl_Obj * Tcl_NewObj(void);