- ATCO
- Association of Transport Coordinating Officers
- DPI
- Dots per inch; a measure of print resolution used to indicate how sharply a QR code can be reproduced.
- HTTPS
- Hypertext Transfer Protocol Secure; the encrypted version of HTTP used to protect data exchanged between a device and a website.
- IEC
- International Electrotechnical Commission; co-publisher with ISO of standards relevant to technologies such as QR codes.
- iOS
- Apple’s mobile operating system used on iPhone devices; referenced here as one of the platforms that should support QR codes natively.
- ISO
- International Organization for Standardization; the body that publishes international standards, including those referenced for QR code generation.
- mm
- Millimetres; the unit of measurement used in this document for QR code size, spacing, and installation height.
- NaPTAN
- National Public Transport Access Nodes
- QR Code
- Quick Response Code; a two-dimensional barcode that can be scanned by smartphones and other devices to open digital content.
- URL
- Uniform Resource Locator; the web address that a QR code directs a user to.
