REGTRAL
Mentioned in Attribute Grammars, LNCS 323, p.108.
Relational Language. Clark & Gregory. First parallel logic
language to use the concept of committed choice. Forerunner
of PARLOG. "A Relational Language for Parallel Programming",
K.L. Clark et al, Proc ACM Conf on Functional Prog Langs and
Comp Arch, pp.171-178, ACM 1981.