The text associated with this span is a measure, consisting of a number and a unit. The number can be a cardinal, decimal or a fraction. Set the number with the same arguments as TtsSpan.TypeCardinal, TtsSpan.TypeDecimal or TtsSpan.TypeFraction. The unit can be specified with TtsSpan.ArgUnit. Also accepts the arguments TtsSpan.ArgGender, TtsSpan.ArgAnimacy, TtsSpan.ArgMultiplicity and TtsSpan.ArgCase.