The FP_PROC routine was modified to take account of the improvement in calibration described previously in this chapter. The main aim of these modifications was to make more L03 data available for processing. Non-prime data could not be processed within the old version of FP_PROC (LIA version 8), which automatically selected the prime detector data. Individual calibration steps were also in need of improvement. Contamination from adjacent FP orders was a particular problem on detector LW1 using FPL and SW2 using FPS and this was not previously addressed in FP_PROC. Also the drift in detector responsivity was not correctly determined and produced spurious results when removed.