ISO 6346 Equipment Category Identifiers (U, J, Z)
Understand the 4th position equipment category identifier letters (U, J, Z) in container numbers.
Quick Technical Summary: Understand the 4th position equipment category identifier letters (U, J, Z) in container numbers. Implementation conforms to ISO 6346 / BIC Container Prefix Coding.
Specification & Structural Breakdown
Position 4 in any valid 11-character ISO container number must be one of three accredited uppercase letters: U, J, or Z.
| Identifier | Equipment Type | Description |
|---|---|---|
| U | Freight Container | All general cargo, reefer, tank, open-top, and flat-rack containers |
| J | Detachable Equipment | Clip-on generator sets (gensets), refrigeration units, detachable tanks |
| Z | Trailers & Chassis | Intermodal chassis, skeletal trailers, and bogies |
Test ISO 6346 Equipment Category Identifiers (U, J, Z) Live
Paste raw inputs up to 32KB and inspect deterministic parsed JSON in real-time across 330+ Cloudflare edge locations. Pure compute, zero cold-starts.
Parsed JSON Response Model
The edge microservice transforms input payloads into strongly-typed hierarchical JSON with zero cold starts:
{
"category": "U",
"description": "Freight Container",
"valid": true
}
Copy-Paste Integration Code
Integrate this validator directly into your application using your production API key:
curl --request POST \
--url "https://iso-6346-container-chassis-check-digit-validator.stanzaapi.com/api/v1/container/validate" \
--header "Content-Type: application/json" \
--header "x-api-key: YOUR_API_KEY" \
--data '{
"containerNumber": "CSQU3054383",
"sizeTypeCode": "45G1"
}'
const response = await fetch("https://iso-6346-container-chassis-check-digit-validator.stanzaapi.com/api/v1/container/validate", {
method: "POST",
headers: {
"Content-Type": "application/json",
"x-api-key": process.env.API_KEY || "YOUR_API_KEY"
},
body: JSON.stringify({
"containerNumber": "CSQU3054383",
"sizeTypeCode": "45G1"
})
});
const data = await response.json();
console.log(data);
import requests
import json
url = "https://iso-6346-container-chassis-check-digit-validator.stanzaapi.com/api/v1/container/validate"
headers = {
"Content-Type": "application/json",
"x-api-key": "YOUR_API_KEY"
}
payload = {
"containerNumber": "CSQU3054383",
"sizeTypeCode": "45G1"
}
response = requests.post(url, json=payload, headers=headers)
print(response.json())
package main
import (
"bytes"
"fmt"
"io"
"net/http"
"os"
)
func main() {
url := "https://iso-6346-container-chassis-check-digit-validator.stanzaapi.com/api/v1/container/validate"
payload := []byte(`{"containerNumber":"CSQU3054383","sizeTypeCode":"45G1"}`)
req, _ := http.NewRequest("POST", url, bytes.NewBuffer(payload))
req.Header.Add("Content-Type", "application/json")
req.Header.Add("x-api-key", os.Getenv("API_KEY"))
res, err := http.DefaultClient.Do(req)
if err != nil {
panic(err)
}
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))
}
Frequently Asked Questions & Technical Notes
No, any 4th character other than U, J, or Z is non-compliant with ISO 6346.
Related ISO 6346 Container & Chassis Check-Digit Validator API Formats
Explore sibling specifications and standards in the same developer cluster:
BIC Bureau International des Conteneurs 3-Letter Owner Prefix Spec
Verify 3-letter BIC owner prefixes for shipping lines, container leasing companies, and rail operators.
View Format →ISO 6346 Modulo-11 Shipping Container Check Digit Formula & Step-by-Step
Step-by-step Modulo-11 check digit calculation for 11-character intermodal container numbers.
View Format →ISO 6346 4-Character Container Size and Type Code Directory
Decode ISO 6346 4-character size and type codes into precise metric and imperial dimensions and cargo types.
View Format →