For nodes, the following attributes are directly understood by Gephi:
Position:
- x:double
- y:double
- z:double
Watch out: If you use these attributes, the layouters can't modify the position of the nodes anymore
Color:
- r:int
- g:int
- b:int
Label:
- label:string
Regarding edges, I don't know. The only thing I know is that edges can have a weight attribute that impacts the thicknes of edges.