In article <505252F5.3090808@parabola.me.uk>, steve@parabola.me.uk says...
Yes the documentation could be clearer, but that is not quite what is happening.
The statement "level 2" is the same as "level 0-2" which means that the item will appear at levels 0, 1 and 2. It will disappear after you zoom out to level 3 or further.
For resolution the default end point is 24 so "resolution 23" means "resolution 23-24". It therefore appears at any level which has a resolution of 23 or 24.
So for levels = 0:24, 1:22, 2:20, 3:18, 4:16
that just means level 0
but with levels = 0:24, 1:23, 2:22, 3:20, 4:18, 5:16
it includes levels 0 and 1, which is what you observed.
[The wiki also says that you have to write the numbers the wrong way round (resolution 24-23; level 4-2) that was true (a bug) at one time, but now you can write them in any order]
Thank you again. I think the fundamental thing I hadn't grasped was that you can't just put a resolution tag on something to cause it to be displayed at that resolution or greater, but that you have to in some sense "create" the level first with the levels specification before you can assign something to that level using either the resolution or level tag. -- Cheers, John