If somewhere inside the definition of structure the name consisting of a
single dot it found, it is replaced by the name of the label for the given
instance of structure and this label will not be defined automatically in
such case, allowing to completely customize the definition. The following
example utilizes this feature to extend the data definition directive db
with ability to calculate the size of defined data:

Code:

struc db [data]
 {
   common
    . db data
    .size = $ - .
 }