There used to be an assembler called RosAsm in the early 00s, whose author insisted on including the full source of the assembler inside the PE executable. That

There used to be an assembler called RosAsm in the early 00s, whose author insisted on including the full source of the assembler inside the PE executable. That way you could edit RosAsm's source (written in the same assembler dialect) and assemble it by itself and produce a new PE executable.