Confused about Attribute Size?

["Zebylon" <sebastian.madunic@esavionics.se>]

Hi,

I'm a newbie in Ada but I saw an Ada example that confused me a bit, here it
is:

type My_Type is
    (startbit,
     endbit,
     timeout,
     spare,
     nextbit,
     ......
     ......
     lastbit);

for My_Type use
    (startbit =>0,
     endbit=>1,
     timeout=>2,
     spare=>3,
     nextbit=>4,
     ......
     ......
     lastbit=>15);

for My_Type'Size use 8;

type My_Type_Array is array (My_Type) of Boolean;

What I don't understand is how you can assign the size to 8 bits? How will
this work when
there are 16 bits in the type? What will be the size of the array?
This example was in Ada 83 could this be a clue?

Thanks

/S