The interface is typically used in the following way (example: Call a Natural subprogram):
Determine the location of the Natural binaries.
Load the Natural Native Interface library.
Call nni_get_interface to
                              retrieve an interface instance.
                     
Call nni_initialize to
                              initialize a Natural session.
                     
Call nni_logon to logon to a
                              specific Natural library.
                     
Call nni_create_parm or a
                              related function to create a set of parameters.
                     
For each parameter
Call one of the nni_init_parm functions
                                      to initialize the parameter to the correct type.
                           
Call one of the nni_put_parm functions to
                                      assign a value to the parameter.
                           
Call nni_get_parm_info to
                                      create the parameter_description structure.
                           
Call nni_callnat to call the
                              subprogram.
                     
For each modifiable parameter.
Call one of the nni_get_parm functions to
                                      retrieve the parameter value.
                           
Call nni_delete_parm to free
                              the parameter structures.
                     
Call nni_uninitialize to
                              uninitialize the Natural session.
                     
Call nni_logoff to return to the
                              previous library.
                     
Call nni_free_interface to
                              free the interface instance.
                     
An example C program nnisample.c that shows the usage of the interface is contained in <install-dir>/natural/samples/sysexnni.