We introduce FRAT, a new proof format for unsatisfiable SAT problems, and its
associated toolchain. Compared to DRAT, the FRAT format allows solvers to
include more information in proofs to reduce the computational cost of
subsequent elaboration to LRAT. The format is easy to parse forward and
backward, and it is extensible to future proof methods. The provision of
optional proof steps allows SAT solver developers to balance implementation
effort against elaboration time, with little to no overhead on solver time. We
benchmark our FRAT toolchain against a comparable DRAT toolchain and confirm
>84% median reduction in elaboration time and >94% median decrease in peak
memory usage.