progressmeter.mode

mode
Type: one of the values below
A determinedprogressmeter is used in cases where you know how long an operation will take. An undeterminedprogressmeter can be used when you don't and will typically be drawn as a spinning barber pole.
determined
The progress meter uses its value attribute to determine the amount of the bar that is filled in.
undetermined
The progressmeter is indeterminate.