Lol i’ve found back the post where i asked exactly the same questions for 3 years ago for another assigment 
((
So the answers are :
a)the transformation matrix to be specified for a joint in tables of an egg file is relative to the parent node only
b)Joints are defined using a local transform, vertices are defined in an egg file using global coordinates
Other pieces of information are:
c)the net transform of each node is derived by pre multiplying the parent’s net transform with the node’s local transform.
That is, Mn = Mn-1Mn-2…M0, where M0 is the root transform.
d)transform matrices in Panda are represented row-major
(which does reverse the meaning of premultiply and postmultiply from a column-major representation)
e)The tables hierarchy should exactly match the skeleton hierarchy.