On Dec 19, 12:18 am, WingFlaps wrote:
On Dec 19, 3:30 pm,
In addition the cruising
altitudes are Xthousand plus or minus 500, and I think. Or have I
missed something?

Yes. You're forgetting that those cruise-altitude rules only apply
above 3000' AGL.

No, I did not forget that. I was trying to point out that if the top
of airspace was 3000' then you wouldn't want to cruise at X+(0-400)
or X-(0-400) anyway.

Ok, but we were talking about +X altitudes, which are used for the
*floor* of an airspace, not for the ceiling. In the specific example
under discussion, there were Class B floors of +05, +08, +11, and +12,
all well below 3000' AGL.