Building and updating map caches with arcgis server 10
When you've finished setting the cache properties, right-click your service in the Catalog tree and click The tiling scheme includes the scale levels, tile dimensions, and tile origin for the cache.
These properties define where tile boundaries will exist and are important to match when overlaying caches in some clients.
If the full extent of your map covers a relatively small area (such as a city) you may not get as many scales as you request. Once you're familiar with the cache creation process, it's best to pick your own scale levels instead of asking the software to suggest scales for you.
If possible, you should even pick the scales before you start designing your map.
If you have services running that need to use this tiling scheme, you must load it from an existing service or a tiling scheme file.
Choose this option if you want to match the tiling scheme of an existing cached service. Matching tiling schemes ensures that your tiles will overlay correctly in web applications and other mashups.
This option is sometimes useful when caching imagery.
Arc GIS Online previously used a tiling scheme based on the WGS 1984 geographic coordinate system that used 512 x 512 pixel tiles.
If you choose this option, your source map document should use the same coordinate system as the map whose tiling scheme you are importing.