MG T-ABC

Could someone please shed some light for me on wheel or wheel rim ‘offset’.
I’m particularly interested to know:
(i) By how much, if anything, should the centreline of the TC’s rim be inset or outset from the centreline of the wheel’s hub? and, in order to simplify its measurement or checking,
(ii) What does that translate into, in terms of the distance between the inner (or the outer) face of the wheel’s hub and the inner (or the outer) face of the wheel’s rim ?

MWS specify the Outset and back spacing of the standard 19" wheel thus....
Outset 23.7mm
Backspacing 24 (+/- 1.5)mm

Thanks 'aj'.
Thats exactly what I needed.
B.