Code 11 Barcode Generator — Telecom Equipment Symbology: Generate high-density Code 11 (USD-8) barcodes online. Free telecommunications inventory barcode creator with automatic C and K Modulo-11 checksums, vector.
What is Code 11 (USD-8)?
Code 11 (standardized as USD-8) is a discrete, variable-length one-dimensional barcode symbology developed in 1977 by Intermec. The name 'Code 11' stems from the fact that it encodes eleven discrete characters: numeric digits $0$ through $9$ plus the hyphen ($-$). The symbology was engineered specifically for labeling telecommunications equipment, circuit boards, telephone components, and telephone exchange switching hardware where label real estate is constrained.
Mathematical Architecture and Bar Geometry
In Code 11, each character is composed of exactly five elements: three black bars and two white spaces. Characters are separated from each other by a single narrow inter-character space. In any standard character, either one element is wide ($2 imes$) and four are narrow ($1 imes$), or two elements are wide and three are narrow.
| Character | Element Pattern (B=Bar, S=Space) | Wide Elements | Character Value |
|---|---|---|---|
| 0 | B-narrow, S-narrow, B-narrow, S-narrow, B-wide | 1 wide | 0 |
| 1 | B-wide, S-narrow, B-narrow, S-narrow, B-wide | 2 wide | 1 |
| 2 | B-narrow, S-wide, B-narrow, S-narrow, B-wide | 2 wide | 2 |
| 3 | B-wide, S-wide, B-narrow, S-narrow, B-narrow | 2 wide | 3 |
| 4 | B-narrow, S-narrow, B-wide, S-narrow, B-wide | 2 wide | 4 |
| 5 | B-wide, S-narrow, B-wide, S-narrow, B-narrow | 2 wide | 5 |
| 6 | B-narrow, S-wide, B-wide, S-narrow, B-narrow | 2 wide | 6 |
| 7 | B-narrow, S-narrow, B-narrow, S-wide, B-wide | 2 wide | 7 |
| 8 | B-wide, S-narrow, B-narrow, S-wide, B-narrow | 2 wide | 8 |
| 9 | B-wide, S-narrow, B-narrow, S-narrow, B-narrow | 1 wide | 9 |
| - (Dash) | B-narrow, S-narrow, B-wide, S-narrow, B-narrow | 1 wide | 10 |
| * (Start/Stop) | B-narrow, S-wide, B-narrow, S-narrow, B-wide | 2 wide | Delimiter |
The Dual C and K Check Digit Algorithm
Because printing imperfections on tiny electronic equipment labels can easily distort bar widths, Code 11 enforces a rigorous two-tier Modulo-11 checksum:
1. The 'C' Checksum
The C check character is computed across all payload characters from right to left using cyclically repeating weights from $1$ to $10$:
$$S_C = sum_{i=1}^{n} (V_i imes ((i - 1) pmod{10} + 1))$$ $$C = S_C pmod{11}$$2. The 'K' Checksum
When the payload contains 10 or more characters, a second checksum 'K' is calculated across all payload characters plus the newly computed 'C' character, using repeating weights from $1$ to $9$:
$$S_K = (C imes 1) + sum_{i=1}^{n} (V_i imes (i pmod{9} + 1))$$ $$K = S_K pmod{11}$$