Different options for debug and release in a toolset jam file

How do I tell Boost Build to use different compiler or linker options, 
depending on whether the end-user is building some target in debug or 
release mode, in a compiler toolset's jam file ? The compiler toolset I 
am trying to create needs to specify, in particular, different library 
directories to search depending on whether the end-user is building a 
debug mode or release mode target. I know what those library directories 
should be for either for debug mode or release mode, and I understand 
how to pass the library directories as a variable to the compile or link 
action, but I do not understand how I tell Boost Build that when the 
action is building a target in release mode it should use the sequence 
of library directories for release mode and when the action is building 
a target in debug mode it should use the sequence of library directories 
for debug mode. Something tells me I have to create different 
conditions, one for release mode and one for debug mode, with the 
appropriate library directories, but I am not sure how this is done. Any 
help would be appreciated.

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