I have a custom list where a user enters information about a vehicle. I want to validate what the user enters as Vehicle ID, against a master Vehicle ID list contained in a seperate custom list.
Is this possible using a validation formula?
Damjan has the right answer: create a lookup column. If there are a huge number of vehicle IDs, making a lookup list cumbersome to use, perhaps check out a managed metadata field (which uses its own data store, not a separate list), or get a developer involved to write an event handler.