These modules are provided to enable legacy Modula-2 applications to build with GNU Modula-2. It is advised that these module should not be used for new projects, maybe the ISO libraries or the native compiler PIM libraries (FIO) should be used instead.
Here is an outline of the module layering:
InOut RealInOut LongIO CardinalIO \ | | / Terminal ----------------------------------- | Termbase / \ Keyboard Display
Above the line are user level PIM  and Logitech 3.0 compatible modules. Below the line Logitech 3.0 advised that these modules should be considered part of the runtime system. The libraries do not provide all the features found in the Logitech libraries as a number of these features were MS-DOS related. Essentially the basic input/output, file system, string manipulation and conversion routines are provided. Access to DOSCALL, graphics, time and date are not as these were constrained by the limitations of MS-DOS.
The following libraries are contained within the base GNU Modula-2 libraries but are also Logitech-3.0 compatible: ASCII, Storage and MathLib0.