The created event record is cleared by zero, i.e. the fixed length with the absolute scheduled time 0 on tick queue 0. Note that for using a variable length event, the extra data must be alloced via malloc or its siblings.
Function returns the pointer of event record if successful.
If it can't create, NULL is returned. This function is provided only for ease of programming. Usually it is faster to use a static event record than creating and freeing an event record at each time.