"The recommended level of support for the Component_Size attribute is:
An implementation need not support specified Component_Sizes that are less than the Size of the component subtype."
"An implementation should support specified Component_Sizes that are factors and multiples of the word size. For such Component_Sizes, the array should contain no gaps between components. For other Component_Sizes (if supported), the array should contain no gaps between components when packing is also specified; the implementation should forbid this combination in cases where it cannot support a no-gaps representation."