normalized
The normalized ratio of the amount of work done to the total amount of work to be done.
Allowed values are between 0.0 and 1.0, both inclusive.
0.0means the work has not started (nothing was done out of the total),1.0means the work has finished (everything was done out of the total).
Although 1.0 is semantically the same as Progress.Done, it is still a legal value to simplify usage.