你看的书中讲得很清楚了。。。1st - Is it a moment in or interval of time, something the system needs to
track for business or for legal reasons? If so, it's a pink momentinterval.
2nd – Otherwise, is it a role? If so, it's a yellow role.
3rd – Otherwise, is it a catalog-like description, a grouping of values that
you can apply again and again? If so, it's blue description.
4th - Otherwise, it's a party, place or thing. It's a green party, place, or
thing (green is the default; if not pink yellow, or blue, it's green).