SP/k - Subset PL/I, k=1..8. A series of PL/I subsets, simplified for
student use. "SP/k: A System for Teaching Computer Programming", R.C. Holt
et al, CACM 20(5):301-309 (May 1977).
SP/k Programming Language
http://www.programming-languages.co.uk/sp-k.html
Large list of computer programming languages arranged alphabetically, with explanations.