Working with Cross-site Lookups
When you have installed Virto Cross-Site Lookup and activated it, you need to adjust the feature to work in a proper way.
Virto Cross-Site Lookup takes its values from SharePoint lists on any site: in the current site collection, another site collection or another web application. Create a list you are going to work with and add a lookup column to it.
Below is an example of Cross-Site Lookup usage. For example, you need to aggregate information from a list of clients which are grouped by countries and cities (country may include several cities).
