Canonical Text Services (CTS) is a protocol to identify and retrieve passages of text cited by canonical reference.
The Canonical (previously 'Classical') Text Services specification defines a network service for identifying texts and retrieving fragments of texts using notions of "work" and "citation" traditional in classical studies and other literary disciplines.
CTS is part of the CITE architecture, developed by Blackwell and Smith to meet the needs of the Homer Multitext project.
URL: http://chs75.harvard.edu/projects/diginc/techpub/cts (Dead link: 2014-07-10) (Archive)
The project also has a Sourceforge site, with more recent information: http://cts3.sourceforge.net/
There is a mailing list: https://lists.sourceforge.net/lists/listinfo/cts3-general