# Overview of NaturalFax data structures

NaturalFax stores system parameters, document status information, and fax session status information in its data structures. All NaturalFax data structures are defined in nfxdef.h. Refer to the files list for the NaturalFax's installed directory structure for the exact path to the NaturalFax header files.

NaturalFax uses data structures to specify the behavior of fax functions. Natural Access parameter functions retrieve and change the values of a specified parameter structure. If a function is governed by parameters, then one of its arguments is a pointer to the relevant parameter structure. You can fill in and pass a parameter structure in the function call, or accept the default parameter values by passing a NULL pointer.

The following Natural Access functions obtain or modify parameter information:

Function | Description
ctaGetParmByName | Retrieves a single field for a given parameter name.
ctaSetParmByName | Modifies a single field for a given parameter name.
ctaGetParmInfo | Retrieves a parameter field definition.
ctaGetParms | Returns parameter values for a given parameter structure.
ctaRefreshParms | Resets the values of all context parameters on a context to the global defaults.

For more information about parameter management in Natural Access, refer to the Natural Access Developer's Reference Manual.