Simple relativity question

How do I get the Vector3.up of a gameobject relative to its rotation?

I'm trying to RayCast upwards from a gameobject to detect whether it's upsidedown or no, but I don't know how to get the relative up direction for that particular gameobject; it seems that Vector3.up is in world coordinates, but I don't know how to get a relative Vector3.up.

It's gotta be one line of code, but I can't find it anywhere.

Thanks - Chad

Transform.up

There are a handful of methods that can help you with local<->world space conversions, in the Transform class. transform.up is just a shortcut for

transform.TransformDirection(Vector3.up);