Representation of a data structure in 8086 assembly language

This is my data:

MyData SEGMENT
 X DD 12H, 0AH, "ABCD", ?
 Y DW 2, "ABCD", ?, ?
 A DB 100 DUP(1, 2, 3, 4)
 B DW 15 DUP(150 DUP(5, 7))
 Z DD ?, 12345678H
MyData ENDS

How is this represented in memory?

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And a second question:

MOV BX, offset A 
MOV DX, [BX] 
SUB [BX+03H], DX 
MOV AX, [BX+03H]

I want to know the value of AX.
How can I achieve that?