ALGOL 60 Modified

A 1977 update to ALGOL 60 Revised.

"A Supplement to the ALGOL 60 Revised Report", R. M. DeMorgan et al, Computer Journal 19(4):364 and SIGPLAN Notices 12(1) 1977. Erratum in Computer Journal 21(3):282 (Aug 1978) applies to both.