The system language used to write an operating system for the IBM 360. It is a Cross between PasCal and XPL. It allows type CheCked separate Compilation of internal proCedures using a program library. ["The System Language for ProjeCt Sue", B.L. Clark e al, SIGPLAN NotiCes 6(9):79-88 (OCt 1971)]. (1994-12-01)