A b-type space is space with more than one link but which forms part of a connected sub-system in which the number of links is one less than the number of spaces, that is, a system which has the topological form of a tree. Such space cannot in itself be dead end space, but must be on the way to (and back from) at least one dead end space.
b-space or b type space
Hillier, B. (1996, 2007), Space is the Machine: A Configurational Theory of Architecture. Space Syntax: London, UK. pp.250