This is the Rosolowsky and Leroy (2006) Algorithm for cloud decomposition.
http://adsabs.harvard.edu/abs/2006PASP..118..590R
It is written in IDL and wraps three separate cloud decomposition algorithms including (1) propdecomp, the default algorithm as described in the paper (2) eclump, as described in Rosolowsky and Blitz (2005) and (3) Clumpfind as described in Williams, de Geus and Blitz (1994).