Omatic Support

Hi all - I have a report where if in a column is says "Guest" then I need a certain letter code but if it says anything else it needs to be a different letter code. Is there an expression for "if this cell doesn't say guest, then make it that"

The very handy "anything else" dictionary: 

See #19 here: https://omaticsoftware.freshdesk.com/support/solutions/articles/28000006124-what-are-some-commonly-used-regular-expressions-

and more methods/details here: 

https://omaticsoftware.freshdesk.com/support/discussions/topics/28000006757