The NCBI C Toolkit data model and core library functionality is documented here http://www.ncbi.nlm.nih.gov/IEB/ToolBox/SDKDOCS/INDEX.HTML This basic documentation is not up to date, and the C Toolkit has much more functionality than is described. You can browse at the headers or search the source http://www.ncbi.nlm.nih.gov/IEB/ToolBox/C_DOC/lxr/ident/ We also have a set of freely available training presentations here: http://www.blueprint.org/products/toolkit/toolkit_course.html As well, our open source software BIND, SeqHound, NBLAST, Kangaroo and others, build on the NCBI C tookit and can be viewed/downloaded here http://sourceforge.net/projects/slritools Hope this helps. -=Michel=- Michel Dumontier PhD Candidate Samuel Lunenfeld Research Institute, Mt. Sinai Hospital Department of Biochemistry, University of Toronto Toronto, ON M5G1X5 micheld at mshri.on.ca http://blueprint.org