Include self in size
If the value of the component with the sized attribute includes the size of the component, use the Include Self in Size option. For example, suppose the component with the sized attribute has a length of seven bytes. The value of the component with the sized attribute would be seven. So, its data would be one byte long, to hold the character seven. If its value includes the length of itself, its value would be 7 + 1 = 8.
For example, a sized component is 7 bytes.
+ 1 byte (the length of the character 7)
If Include Self in Size is selected: 8 bytes