Declaration: TIlabTrnDataSet.Quantity [idx, obj: integer]: double;
The array property Quantity allows to access the user-defined quantities of the dataset. The parameter obj (valid range: 1..NDataPoints) addresses the individual data point. The parameter idx addresses the user-defined quantity (valid range: 1..NQuantities).

If you try to access a non-existent data point (for example, if the obj is less than 1 or greater than NDataPoints) the call will be ignored on write or return a zero value on read.