Automotive Glass Laminated Glass
How to Read the Markings on Automotive Glass
In short
Every piece of vehicle glass carries an etched block of markings that records who made it, which authority approved it, what type of glass it is and roughly when it was produced. The E mark is a European approval under UN Regulation 43, where the number beside the E identifies the country that granted it, so E11 is the United Kingdom and E1 is Germany. DOT numbers and AS ratings are the United States equivalent, and IS 2553 Part 2 is the Indian standard for road-vehicle safety glass.
Every piece of glass fitted to a vehicle carries a small block of etched or printed markings, usually in a bottom corner. It looks like a jumble of letters, numbers and symbols, but each part is there for a reason: together they record who made the glass, which authority approved it, what type of glass it is, and roughly when it was made.
Being able to read that block is useful whether you are checking that a replacement windscreen is legal, verifying a supplier's claim, or working out how old the glass in a vehicle actually is.
The E mark, and what the number beside it means
A capital E inside a circle is a type approval granted under the UN vehicle regulations, administered through the United Nations Economic Commission for Europe. For glazing, the governing rule is UN Regulation 43, which covers safety glazing materials and their installation in vehicles.
The number printed beside the E does not identify the manufacturer, and it does not indicate quality. It identifies the country whose authority granted the approval. Glass marked E11 was approved by the United Kingdom, glass marked E1 by Germany, and so on. A manufacturer in any country may hold an approval issued by any of these authorities.
| Mark | Approving country |
|---|---|
| E1 | Germany |
| E2 | France |
| E3 | Italy |
| E4 | Netherlands |
| E5 | Sweden |
| E6 | Belgium |
| E7 | Hungary |
| E8 | Czech Republic |
| E9 | Spain |
| E10 | Serbia |
| E11 | United Kingdom |
| E12 | Austria |
| E13 | Luxembourg |
| E14 | Switzerland |
| E16 | Norway |
| E17 | Finland |
| E18 | Denmark |
| E22 | Russian Federation |
| E43 | Japan |
The list continues well beyond these; the full schedule sits in the 1958 Agreement and now runs into the sixties. The entries above are the ones seen most often on glass circulating in Europe and Asia.
A lower-case e inside a rectangle rather than a capital E inside a circle indicates approval under European Union directives rather than the UN regulations. The two systems ran in parallel for years and both marks are still found in service.
The rest of the E mark block
Alongside the E and its country number you will normally find an approval number identifying the specific certificate, and a code indicating the glazing type, which distinguishes a laminated windscreen from toughened side glazing and from glass-plastic constructions. Because those type codes are defined in the regulation and assigned per certificate, the reliable way to confirm what a given code means is to ask the supplier for the approval certificate itself rather than to infer it.
DOT numbers and AS ratings
Glass approved for the United States market carries a DOT number instead of, or alongside, the E mark. The digits after DOT identify the manufacturer, assigned by the National Highway Traffic Safety Administration. Like the E number, it identifies who, not how good.
Next to it sits an AS rating from the ANSI Z26.1 standard, which classifies glazing by where it may legally be fitted:
- AS1 — laminated glass with high light transmission, permitted anywhere on the vehicle including the windscreen.
- AS2 — toughened glass with high light transmission, permitted in side and rear positions but not in the windscreen.
- AS3 — tinted glazing with reduced light transmission, restricted to positions away from the driver's primary view.
The full schedule in ANSI Z26.1 runs further than these three, but AS1, AS2 and AS3 are the ratings that appear on almost all passenger and commercial vehicle glass.
IS 2553 Part 2, the Indian standard
In India, safety glass for road vehicles is governed by IS 2553 Part 2, issued by the Bureau of Indian Standards. Part 1 of the same standard covers architectural glass, which is why the part number matters: a mark citing Part 1 says nothing about a product's suitability for a vehicle.
IS 2553 Part 2 sets requirements for impact behaviour, light transmission, optical distortion and the retention of fragments after breakage. Indian vehicle manufacturers also require Conformity of Production certification, issued by the Automotive Research Association of India, which audits that production continues to match the approved sample rather than testing a one-off submission.
The date code
Most vehicle glass carries a small date code, commonly a number with a row of dots beside it. The number gives the month and the dots encode the year within a decade, with the position of the dots indicating whether the year falls before or after the middle of that decade. The convention is widely used but not universal, and manufacturers apply it in slightly different ways.
Where it matters, the practical use is comparison rather than precision. If one pane in a vehicle carries a date well after the others, that pane has been replaced.
Why windscreens are laminated and side glass usually is not
The markings encode a design decision that is worth understanding on its own terms.
A windscreen is laminated: two layers of glass bonded to a plastic interlayer. When it breaks it cracks but stays in one piece, held together by the interlayer. That matters for two reasons. The driver keeps some forward vision instead of losing the whole screen at once, and an unbelted occupant is far less likely to pass through it.
Side and rear glazing is usually toughened: heated and rapidly cooled so that it breaks into small blunt granules rather than shards. The pane clears the opening completely, which in a side window is a feature rather than a fault, because it allows escape and rescue through the aperture.
This is the same distinction that governs architectural glazing, applied to a different problem. In a building, a balustrade is laminated so the barrier survives a break; a shower screen is toughened so the fragments are harmless.
What to ask a supplier
The markings tell you an approval exists. They do not tell you the approval covers the exact product being supplied, which is the question that matters on a purchase order.
- Ask for the approval certificate, not the mark. The certificate states the scope: which glazing types, which constructions and which thicknesses it covers.
- Check the part number of the standard being cited. IS 2553 Part 1 is architectural, Part 2 is automotive.
- For a fleet or an assembly line, ask whether Conformity of Production is held, since a type approval alone tests a submitted sample rather than continuing output.
- Confirm the market the approval is for. An approval granted for one market does not automatically satisfy another.
Where TPRS fits
TPRS Glass processes automotive glazing alongside its architectural lines, supplying laminated windscreens and toughened side and rear glazing for buses, trucks, material handling equipment, earth-moving machinery and rail vehicles.
The approvals TPRS holds on the automotive side include the E Mark for European vehicle glazing, DOT for the United States, IS 2553 Part 2 for India, Conformity of Production from the Automotive Research Association of India, and IATF 16949 for automotive quality management. The full list, with the architectural approvals alongside it, is on the quality and certification page, and certificate copies are available with a quotation.
Frequently asked questions
A capital E inside a circle is a type approval granted under the UN vehicle regulations, with safety glazing covered by UN Regulation 43. The number beside the E identifies the country whose authority granted the approval, not the manufacturer and not a quality grade. E11 is the United Kingdom, E1 is Germany, E2 is France and E3 is Italy.
A capital E inside a circle indicates approval under the UN regulations administered through the UNECE. A lower-case e inside a rectangle indicates approval under European Union directives. Both systems have operated in parallel and both marks are still found on glass in service.
They are ratings from the American ANSI Z26.1 standard that classify where glazing may be fitted. AS1 is laminated glass with high light transmission, permitted anywhere including the windscreen. AS2 is toughened glass with high light transmission, permitted in side and rear positions but not the windscreen. AS3 is tinted glazing with reduced light transmission, restricted to positions away from the driver's primary view.
Most vehicle glass carries a number with a row of dots beside it. The number indicates the month and the dots encode the year within a decade, with their position showing whether the year falls in the earlier or later half. The convention is common but not universal. Its most reliable use is comparison: a pane dated well after the others in the same vehicle has been replaced.
IS 2553 Part 2 is the Indian standard issued by the Bureau of Indian Standards for safety glass used in road vehicles. It sets requirements for impact behaviour, light transmission, optical distortion and fragment retention. Part 1 of the same standard covers architectural glass, so the part number matters when a supplier cites it.
A laminated windscreen cracks but stays in one piece because the fragments are held on a plastic interlayer. The driver retains some forward vision and an unbelted occupant is far less likely to pass through it. Toughened glass clears the opening entirely when it breaks, which is acceptable in a side window, where it also aids escape and rescue, but not in front of the driver.