The phrase "code number" refers to a unique combination of letters, numbers, or symbols assigned to something or someone. It is used to easily identify and classify things, such as products, files, or individuals. Full definition
All rooms have air conditioning, private bathroom, mini bar, safe with code number and magnetic card, magnetic card lock, hair dryer, and colour TV with remote control. (loveholidays.com)
Participation in the study and any information provided to us will remain strictly confidential and samples are only identified by coded numbers. (ecscahealthandrescue.org)
The spoons feature permanent, bright, color - coded numbers so that measurement markings are easily recognizable. (amazon.com)