nested rights for Access Levels

Are nested rights available? I have Content A and B. An I have Access Levels 0 and 1.
Level 0 should have access to Content A.
Level 1 should have access to Content A and B.
What I'm trying to do is some kind of:
[level-1][level-0]
Content A
[/level-0]
Content B
[/level-1]
but this doesn't seem to work. Any ideas out there?

Sheers,
Henning