Langage Implementation Systeme.
A predecessor of Ada developed by Ichbiah in 1973. It was influenced by Pascal's data structures and Sue's control structures. A type declaration can have a low-level implementation specification.
["The System Implementation Language LIS", J.D. Ichbiah et al, CII Honeywell-Bull, TR 4549 E/EN, Louveciennes France (Dec 1974)].
["The Two-Level Approach to Data Independent Programming in LIS", J.D. Ichbiah et al, in Machine Oriented Higher Level Languages, W. van der Poel ed, N-H 1974, pp.161-169].