About Target_length

It reports the estimated target length for each single target exported. Target_length is calculated in one of two ways:

When the target length calculator operator is used to create a single target variable. See Target length from single beam data and the target length calculator algorithm.
When the multibeam target detection operator is used to create a multibeam targets variable and Target length is selected on the Target page of the Variable Properties dialog box. Target_length is calculated using the maximum distance between any two samples in the target.

Target_length will be exported when exporting data from a single target variable or a target length variable.