This is kind of interesting.. the code for that function is pretty straightforward:

CREAE FUNCTION [sys].[fn_get_audit_file] (

@file_pattern nvarchar(260),

@initial_file_name nvarchar(260) = NULL,

@audit_record_offset bigint = NULL)

RETURNS table

AS

RETURN SELECT *

FROM OpenRowSet(TABLE FN_GET_AUDIT_FILE, @file_pattern, @initial_file_name, @audit_record_offset)

CEWII