Simply provides a standard method of parsing, categorizing, and normalizing data.
http://docs.splunk.com/Documentation/CIM/latest/User/Overview
The add-on is meant as an add-on, not an app. It is not meant to have a UI.
It's pretty powerful to display all your data into common formats. You can then create dashboards with those standard fields without having to re-invent the wheel every time.
There are several "CIM" compliant addons within the splunk apps and addons that some have already formatted popular logs into this format for you:
http://apps.splunk.com/apps/#/search/CIM%20compliant
http://apps.splunk.com/apps/#/search/Common%20Information%20Model
http://apps.splunk.com/apps/#/search/CIMifies
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