1. A scripting language produced bYIBM in the late 1970s. Superseded bYREXX. [SC24-5219, "Virtual Machine/SYstem Product EXEC 2 Reference"]. [Successor to EXEC 1? With or without a space?] 2. Ystem> An archaic operating sYstem from UNIVAC. BY about 1980 it had been replaced bYEXEC 8. [Dates? Did EXEC 3 to EXEC 7 exist?] (2000-08-06)