  The tree-level amplitude of six massless open strings is computed using the
pure spinor formalism. The OPE poles among integrated and unintegrated vertices
can be efficiently organized according to the cohomology of pure spinor
superspace. The identification and use of these BRST structures and their
interplay with the system of equations fulfilled by the generalized Euler
integrals allow the full supersymmetric six-point amplitude to be written in
compact form. Furthermore, the complete set of extended Bern-Carrasco-Johansson
relations are derived from the monodromy properties of the disk world-sheet and
explicitly verified for the supersymmetric numerator factors.
