2.5.9 Meters And More AL API

All Meters And More AL API functions and data types are defined in the mm_al_api_host.h file, and this file contains the interface to AL API.

There are two type of functions:

Request functions to send messages or data, for example:
```
    void AL_DataRequest( AL_DATA_REQUEST_PARAMS *reqParams )
```
Callbacks to manage confirm and indication messages.

Each callback is registered with a function, for example:

    AL_RESULT AL_DataIndicationCallbackRegister( AL_DATA_IND_CALLBACK callback );

Where the argument is a pointer to the callback handler function:

The definition of each callback format is in the same mm_al_api_host.h file. If a callback is set to NULL, the corresponding confirm or indication message will not be forwarded to any callback function.