# Loading and changing parameters

A parameter file must be in one of the directories specified with the AGLOAD environment variable for Natural Access to load it. When the function associated with the parameter type is invoked, the parameters go into effect.

Each parameter structure has a set of default values that is sufficient for many configurations. The parameters can, however, be modified to:

- Enable or disable function features.

- Adapt the function for unusual configurations.

Note: Values for certain protocol-dependent parameters should not be changed. Changing their values may affect the regulatory approvals in the target country. For more information, refer to the protocol-specific documentation.

Complete the following steps to change parameter values in a .pf file:

Step | Action
1 | Modify the value in the corresponding .par file.
2 | Parse the .par file.
3 | Do one of the following tasks: Invoke ctaSetParmByName for each parameter specified in the file, to set a new default value. (For an example of this, see the DemoLoadParameters function in the demonstration library supplied with Natural Access.) Use the ctdaemon program to set the parameters system-wide. See the Natural Access Developer's Reference Manual for more information. Invoke ctaLoadParameterFile from within the application.

Parameter modification must take place before nccStartProtocol is invoked to start the protocol (as described in Starting a protocol on a context). When the function is invoked, the TCP is programmed as specified by the parameters.

Modify parameters before you invoke nccStartProtocol to start the protocol (as described in Starting a protocol on a context). When you invoke the function, the protocol is programmed as specified by the parameters.