FSD file extension is associated with data file generated by COCO AmsterCHEM. COCO (CAPE-OPEN to CAPE-OPEN) is a software package for simulating chemical processes.

FSD flowsheet files are generated by COFE (CAPE-OPEN Flowsheet Environment) spreadsheet application included with COCO AmsterCHEM. FSD files are similar in structure to spreadsheet documents and are used to store data used during simulations. FSD files are commonly referred to as flowsheets.