eing used).
 
     After aggregation, outliers that were previously removed are typically 
     reinserted into the spikes list so that the list aligns with the original
     (pre-sorted) list.  The outlier waveforms and spike times are thus by
     default added back to the SPIKES.WAVEFORMS and SPIKES.SPIKETIMES fields
     respectively, after all other aggregation is complete.  These waveforms
     are assigned the label 0 in SPIKES.HIERARCHY.ASSIGNS and the other, 
     non-outlier, spikes are renumbered