# Using the function reference

This section provides a comprehensive, alphabetically-ordered reference to the NaturalFax functions. A prototype of each function is shown with the function description and details of all arguments and return values. A typical function description includes:

Prototype | The prototype is shown followed by a list of the function arguments. Data types include: WORD 16-bit unsigned DWORD 32-bit unsigned INT16 16-bit signed INT32 32-bit signed BYTE 8-bit unsigned If a function argument is a data structure, the complete data structure is defined. Refer to the Overview of NaturalFax data structures for a description of all data structures and parameters.
Return values | The return value for a function is either SUCCESS or an error code. For asynchronous functions, a return value of SUCCESS indicates the function was initiated; subsequent events indicate the status of the operation. Refer to the Alphabetical error summary for a list of all errors returned by NaturalFax functions.
Events | If events are listed, the function is asynchronous and is complete when the DONE event is returned. If there are no events listed, the function is synchronous. Additional information such as reason codes and return values may be provided in the value field of the event. Refer to the Overview of events for information about all NaturalFax events and reason codes.