The interface functions return the following return codes. The constants are defined in the header file natni.h. This file is contained in the directory <install-dir>\natural\samples\sysexnni.

Return Code	Meaning
NNI_RC_OK	Successful execution.
NNI_RC_ILL_PNUM	Invalid parameter number.
NNI_RC_INT_ERROR	Internal error.
NNI_RC_DATA_TRUNC	Data has been truncated during parameter value access.
NNI_RC_NOT_ARRAY	Parameter is not an array.
NNI_RC_WRT_PROT	Parameter is write protected.
NNI_RC_NO_MEMORY	Memory allocation failed.
NNI_RC_BAD_FORMAT	Invalid Natural data type.
NNI_RC_BAD_LENGTH	Invalid length or precision.
NNI_RC_BAD_DIM	Invalid dimension count.
NNI_RC_BAD_BOUNDS	Invalid x-array bound definition.
NNI_RC_NOT_RESIZABLE	Array cannot be resized in the requested way.
NNI_RC_BAD_INDEX_0	Index for array dimension 0 out of range.
NNI_RC_BAD_INDEX_1	Index for array dimension 1 out of range.
NNI_RC_BAD_INDEX_2	Index for array dimension 2 out of range.
NNI_RC_VERSION_ERROR	Requested interface version not supported.
NNI_RC_NOT_INIT	No Natural session initialized in this interface instance.
NNI_RC_NOT_IMPL	Function not implemented in this interface version.
NNI_RC_PARM_ERROR	Mandatory parameter not specified.
NNI_RC_LOCKED	Interface instance is locked by another thread.
rc, where rc < NNI_RC_SERR_OFFSET	Natural startup error occurred. The Natural startup error number as documented in Natural Startup Errors (which is part of the Operations documentation) can be determined from the return code by the following calculation: startup-error-nr = - (rc - NNI_RC_SERR_OFFSET)
> 0	Natural error number.