Sequence tagged site
From Conservapedia
The Sequence tagged site is the short DNA segment that occurs only once in the human genome and whose exact location and order of bases are known. Because each is unique, STSs are helpful for chromosome placement of mapping and sequencing data from many different laboratories. STSs serve as landmarks on the physical map of the human genome.
Sources
http://www.genome.gov/glossary.cfm?key=sequence%2Dtagged%20site%20%28STS%29
