This is the 5th version of the Pascal-P compiler from Zurich. This is the Pascal-P4 compiler modified to be ISO 7185 Pascal compliant, both in the implementation language, and in the language it processes. It is the first version of Pascal-P created outside of Zurich.
Pascal-P was an implementation kit, created between 1972 and 1974, for the original language Pascal. The source for the original compiler was passed around and modified quite a bit, but Niklaus Wirth noted that it was very popular, and represented a good method to popularize the language. He gathered the source into a clean version called Pascal-P2, which was the basis of UCSD Pascal, which in turn was the base language for Borland Pascal. The Zurich group then created an improved version called Pascal-P4.
Pascal-P5 is Pascal-P4 modified to accept all of the ISO 7185 language.