The conflict in the objectives for dipped beam headlamps:  providing good visibility for the driver and limited dazzle for oncoming cars is regulated by law.  Headlamps and their light sources are therefore safety relevant motor vehicle parts requiring official approval and prohibiting manipulation. Today there are still primarily three different regulations world wide:  European (ECE), US (SAE) and Japanese regulations.  Headlamps can basically be classified into reflection type and projection type systems.  Both versions have been used in the development of motor vehicles. 

Shortly after the turn of the 20th century Hella produced motor vehicle headlamps based on both systems in 1905.  Progress in computer and production technology made it possible during the 80's and 90's to design the reflecting surfaces for headlamps differently.  This resulted in spatially free formed reflectors used in FF and Super DE headlamps.

You will certainly have noticed the combinations of numbers and letters on the cover lens while cleaning the headlamps and taillamps.  What do these mean? They can be explained using an example.  Take the widely - used H4 standard headlamp.  This bears the inscription 'HC/R 25 E1 02A 44457' on the lens.  The code HC/R indicates the headlamp version: H stands for halogen, C for dipped beam and R for main beam.  The slash between the C and R means that the dipped beam and main beam cannot be switched on simultaneously (H4 headlamps).

The following reference number, 25, provides information on the luminous intensity from the headlamp.  This is typically somewhere in the following range: 10; 12.5; 17.5; 20; 25; 27.5; 30 and 37.8.  The reference value of 75 represents the maximum value, which cannot be exceeded when all headlamps on the vehicle are switched on simultaneously.

The symbol E1 means that the headlamp has been approved according to the relevant ECE regulation (E) in Germany (1).  02A means that the headlamp contains a marker light (parking light) (A), whose regulation has been amended twice since publication (02).  The code is concluded by a 5-digit type-test number (44457), granted specifically for each headlamp version approval.

Second example: combination rear lamp.  The number is RS1 IAF 02 E1 631483.  The code RS1 indicates the version: R stands for taillamp, S1 for stop lamp, IA for reflex reflector and F for rear fog lamp.  All these functions are integrated into the combination rear lamp.  E1 tells you that the lamp has been approved for Germany according to ECE regulations.  The arrow indicates the installation direction for the lamp and therefore always points toward the outside of the vehicle.  If no arrow is present, the lamp can be installed on the rear left or right.  This is concluded by a 5-digit type-test number (31483).

These standardised codes document the authenticity as well as the quality of the products.  If they are not present on the headlamps or other lamps they are very probably counterfeit products, which may be deficient in terms of quality and safety requirements.  The markings therefore help protect workshops and parts dealers from product piracy.