The algorithm was published in 2010 and implemented in a program also named UCLUST.
The second criterion states that each member sequence in a given cluster will have similarity to the cluster's centroid sequence that is equal or greater than T. UCLUST algorithm is a greedy one.
For this reason, it is advised that the sequences will be sorted before entering clustering stage.
The program UCLUST is equipped with some options to sort the input sequences prior to clustering them.
UCLUST program is widely utilized among the bioinformatic research community, where it used for multiple applications including OTU assignment (e.g. 16s), creating non-redundant gene catalogs, taxonomic assignment and phylogenetic analysis.