Lighting Code Information

This page explains the "E" and other code markings found on car lights. I've copied it wholesale from here, as it was the best explanation I could find.

International ECE markings

ECE/EEC marking: Country of Approval

Firstly, what are those numbers that come after the "E" in the circle or the "e" in the box? What makes a lamp marked (E6) [e6] different from a lamp marked (E1) [e1]?

The uppercase "E" in a circle means the device is type approved to an ECE Regulation, while the lowercase "e" in a box indicates the device is type approved to an EEC Directive. It's rare to find one marking without the other, since the requirements are essentially identical. The number after the "E" or "e" signifies the country in which approval was granted. This doesn't necessarily indicate anything about the quality or performance of the device, though some countries' test-and-approval labs have reputations for being much stricter and others have reputations for being quite lax. The number also doesn't indicate where the device was designed or manufactured. Under ECE and EEC regulations, an item of motor vehicle equipment type approved in any ECE or EEC member country is acceptable for use in any other country that permits or requires vehicles and vehicle components conforming to ECE or EEC safety regulations. Here is a breakout chart of the numbers:

Lamp Function Markings

There are letters, numbers and symbols on the lens or housing that indicate various aspects of the lamp's function and performance. The North American SAE and rest-of-world ECE regulations indicate the various functions with different markings. The two systems use some of the same markings for different functions.

Signal Lamp Markings, Front and Rear

Forward Illumination Lamp Function Markings:

These markings may occur in variant forms. For instance, HCR may or may not be surrounded by a box, and may occur as HC/R. Markings may also occur together. For example, a front lamp cluster that incorporates a low beam headlamp and a high beam headlamp, each with its own halogen bulb and reflector, would be marked HCHR, while a front lamp cluster incporporating a Xenon HID low beam headlamp and a halogen high beam would be marked DCHR.