The Colorado DMV is simply using a different term for the same number.
The customer identifier is your driver's license number. Instead, you see two terms on the license that might be unfamiliar to you: 'Customer identifier' in field 4d and 'DD' in field 5. Conspicuously missing from the Colorado license, however, are the words 'driver's license number.' It contains a lot of useful information in list form, including your personal identification information and photo.
Newly licensed drivers in Colorado may have noticed the state's creative driver's license design.
