The Free On-line Dictionary of Computing (30 December 2018):
FGL 1. Flow Graph Lisp. A distributed dataflow language for AMPS (Applicative Multi-Processing System). "A Loosely-Coupled Applicative Multi-Processing System", R. Keller et al, NCC, AFIPS June 1979, pp.613- 622. 2. Function Graph Language. Related to FEL.