What TREX index types activate witch services?

Hi,

I see from Karstens reply (Index/Search Question) to an earlier discussion that a pure "search" index disables classification, similarity searching, similar terms and "etc".

So I guess that the "classification" type index activates the services:

- classification

- similarity searching

- similar terms

What services are "etc", and what services does the "search" index activate? Is there a document explaining this, and what the different services does?

Basically: What services does the "search" index activate/utilize and what services does the "classification" index activate/utilize, and a description of the services.

Best regards,

Bjorn