Operator: Address function not prescribed by the standard IEC 61131-3.
ADRINST can be used within a function block instance to return the address of this instance in a DWORD.
Examples in ST (within a function block instance):
dvar:=ADRINST(); (* Address of the instance is written to variable dvar *) fun(a:=ADRINST()); (* The instance address is given to input parameter a of function fun *)