Hi, Inn a light of recent discussion on earlier freezing, I have following question/proposition: Is it exist in Boost.Build or could we add feature that allow us to specify cvs tag dependency as a dependency grist? Example1: Jamfile ------- MY_SRCS = .... tag_to_test = my_lib_dev # HEAD run my_test : <tag:$(tag_to_test)>$(MY_SRCS) Now If I want to test my new development branch I just set tag to appropriate value. Example2: Jamfile ------- exe my_test : ...sources... <tag:1_31_0><lib>../build/boost_unit_test_framework Now I want stable version of library - I specify which one I want. Example3: Jamfile ------- exe my_test : ...sources... <tag:1_30_0>...abc.h Here I know my code works with that version of header file I want to use it specifically. And so on. This feature could allow us to: 1. Test development branches for regressions 2 .Test new features before moving it in cvs HEAD 3. Depend on stable version of dependency, without need to keep up with changes in it. 4. Test development version Boost.Test with stable version of it e.t.c I am sure it's not easy to do. But may be it worth a shot. Gennadiy.