This chapter contains M2F, ULM, PIM and ISO libraries. The ISO libraries are currently work in progress, many are complete but probably contain many bugs. The M2F libraries are very mature as the compiler uses them extensively. Permission has been kindly granted by the authors of the ULM libraries to include them with GNU Modula-2. These libraries (under the GNU GPL) were written at the University of Ulm and were originally shipped with the ULM sparc Modula-2 compiler.