MINSCALE MAXSCALE USE in grouped layers

[Glen Thompson]

I'm having a hard time understanding what they mean.

I'm using them in mapserver in a WMS implemention.  I have a layer of highres data in a tileindex and an additional lowres layer.
These layers are grouped together and I'm using minscale/maxscale to determine which layer the server should use to service the request.

Here is a snippet from config.map :

These are the values I used for the lowres
LAYER
  NAME SeattleOverview
  GROUP "Imagery"
  MINSCALE 100000
  MAXSCALE 1000000000000

.....
These are the values I used for the highres tileindex
 LAYER
  NAME SeattleTiledHighres
  GROUP "Imagery"
  MINSCALE 0  
  MAXSCALE 100000


These values seem to be working ok but I want to understand their meaning.

many thanks,
Glen Thompson