The prefix of the 'Elaborated attribute must be a unit name. The
value is a Boolean which indicates whether or not the given unit has been
elaborated. This attribute is primarily intended for internal use by the
generated code for dynamic elaboration checking, but it can also be used
in user programs. The value will always be True once elaboration of all
units has been completed. An exception is for units which need no
elaboration, the value is always False for such units.