 PL/C was a very fast compiler.PLAGO, created at the Polytechnic Institute of Brooklyn, used a simplified subset of the PL/I language and focused on good diagnostic error messages and fast compilation times.The Computer Systems Research Group of the University of Toronto produced the SP/k compilers which supported a sequence of subsets of PL/I called SP/1, SP/2, SP/3, ..., SP/8 for teaching programming.