UCSD p-system p-code
From Just Solve the File Format Problem
UCSD p-System p-code was used in conjunction with UCSD Pascal, a version of the Pascal programming language released by the University of California, San Diego for a number of computer platforms. This was designed to have a self-contained, platform-independent environment that included a custom operating system and filesystem, as well as a compiler which compiled Pascal into virtual-machine code which could then be run by an intepreter for the specific hardware being used.
The code was termed "p-code", in which the "p" didn't stand for "Pascal" even though it was used in conjunction with this language; it could stand for either "portable" or "pseudo".