Hello, The Chimera release notes describe what is new or changed in a release: <http://www.cgl.ucsf.edu/chimera/docs/relnotes.html> ... clicking the "1.4" link: <http://www.cgl.ucsf.edu/chimera/docs/relnotes/1.4.html> The meaning of "constraint" "restraint" and "tether" may change based on which program you are using. Each program should explain it in its own documentation. In programs I've used, "constraints" meant atoms are completely fixed in place (frozen, cannot move) whereas "restraints" use a force constant like a spring, and allowed some movement. I don't have any opinion on the technical definition of "tethering." Again, don't rely on my descriptions as final because different programs may use the words to mean different things. Chimera minimization only allows "fixing" some of the atoms so they can't move at all. It does not allow holding atoms in place with force constants. http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/minimize/minimize.h...

I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. meng@cgl.ucsf.edu UCSF Computer Graphics Lab and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco http://www.cgl.ucsf.edu/home/meng/index.html

nice to give you a letter! is there a new one ,really? what is the new feature in the least software?

I want constraint ,restraint and tether some atoms and backbone. how can I do constraiting ,restrainting and tethering in software.how can i set value for constraiting ,restrainting and tethering. what is the difference between them?

thank you!