FXP
From Just Solve the File Format Problem
FXP is a binary file format for storing presets used by Steinberg VST2 plugins. VST is a framework for plugins in digital audio workstations. It has been retired in favor of the newer .vstpreset format used by VST3.
A sampling of FXP presets for the wavetable synth Serum all seem to begin with the header 43 63 6E 4B 00 00 11.
