Cr3
From Market Ruler Help
cr3 is the Query String variable configured to capture the inbound Keyword for an advertising campaign.
cr3 is the indexed query strings and allows for up to 8 different landing dimensions to be recorded using query strings which are indexed from 0 to 7.
Common synonyms can be also used:
When it appears in a URL:
https://www.example.com?cr3=blossoms
When it appears in a URL:
https://www.example.com?cr3=blossoms