ifTemplate
This script is designed to be used as an itemFilter for the ‘lsThroughFilter’ MEL command. It filters the input list to return only those objects which are currently rendered in Template mode.
First, prepare the itemFilter. You only have to do this once per Maya session.
itemFilter -byScript ifTemplate ifTemplate;
You may then use the filter with the ‘lsThroughFilter’ MEL command:
lsThroughFilter ifTemplate;
See Maya's documentation on itemFilters for more information.