# Header files

Use the following header files to develop applications:

File | Description
--- | ---
ctadef.h | Natural Access library definition.
ctadisp.h | Natural Access dispatcher include file.
ctaerr.h | Natural Access error definitions.
nmstypes.h | Primitive type definitions that promote portability.
nmshw.h | NMS board definitions.
servicename def.h | Service API definition files.
servicename spi.h | Service SPI include file.

For information on other service-specific include files, see the developer's reference manual for the service.