Throughout Concept of Nature Whitehead adds different types of characteristics to his most basic concept - events.
For example, he talks of objects, the situation of the event in space and time, its relation to other events et cetra.
I kind of expected, from a mathematician that uses a systematic/formulaic kind of philosophical explanation of his system of nature, to have a very definitive set of characteristics for his concepts - especially events. Instead I see that in every chapter he adds more characteristics and always keeps it vague as saying "there are more but I won't explore it now". I'm reaching the end of the book and it still seems that he hasn't explored them all.
So, my question would be, did Whitehead actually defined a set of characteristics to the concept of an event - and if so what are they?