The pop-up menu Preprocess provides several options for creating new data sets by modifying the Working Data set. The new data sets will be inserted into the Data board.
Select channels...
Allows you to select a subset of the input and output channels of the data set. The numbering of the inputs and outputs will be consistent throughout all data sets created from an original set.
Select range...
Allows you to select portions of the data set to be used for estimation and validation purposes.
Remove means
Removes the mean values from both the input and output sequences.
Remove trends
Estimates and removes a linear trend from the input and output signals. For more information, see the MATLAB help on the DTREND function.
Filter...
Allows you to prefilter the data set.
Resample...
Allows you to change the sampling interval, by interpolation and decimation.
Quick start
Creates three new data sets from the Working Data set. First the mean values are removed, then the new data is split into two halves, the first half becomes the new Working Data set, and the second half becomes the new Validation Data set. Quick start also opens the plot window.

Help topics.

(file iddatprp.htm)