  For a birational analogue of minimal elliptic surfaces X/Y, the singularities
of the fibers define a log structure in codimension one on Y. Via base change,
we have a log structure in codimension one on Y', for any birational model Y'
of Y. We show that these codimension one log structures glue to a unique log
structure, defined on some birational model of Y (Shokurov's BP Conjecture). We
have three applications: inverse of adjunction for the above mentioned fiber
spaces, the invariance of Shokurov's FGA-algebras under restriction to
exceptional lc centers, and a remark on the moduli part of parabolic fiber
spaces.
