A Structure Block Reference occupies 1 Stack Cell  and is either uninitialized or else contains a Reference to a Structure Block Variable, which may be a single element or an element of a Structure Block Array.

0039 (02,0023)  6 000000 000000  STRUCTUREBLOCKREFERENCE (Structure block) 
                                                          Uninitialized variable 

0039 (02,0023)  C 100000 001E40  STRUCTUREBLOCKREFERENCE (Structure block) 
                                            Present-copy, ASD=00F200, Length=26
                                            (Mom @ [3,4] via offset 0038 in this stack)   
0038 (02,0022)  C E00000 001EA5  STRUCTUREBLOCKARRAY (Structure block array)
                                             Present-mom, ASD=00F52F, Length=4   

It is created as an uninitialized variable,

			ZERO
			LT8  6
			ZERO
            

 It is initialized by generating a reference to a Structure Block variable,

 StructureBlockReference:=StructureBlockArray[3,4];
               LT8   3            B203     
               NAMC  (02,0022)    5022     
               NXLN               A5 
               LT8   4            B204     
               NXLN               A5 
               NAMC  (02,0023)    5023     
               OVRD               BA