What it contains
The field holds 6 bits for the version number, from 7 to 40, followed by 12 bits of BCH error correction, for 18 bits in total. The error correction lets a reader recover the version even if a few of these modules are damaged.
Each copy is laid out as a block of 6 by 3 modules. One block sits just above the bottom-left finder pattern and the other just to the left of the top-right finder pattern, with the bits transposed between the two.
- Present only in versions 7–40
- 6 bits of version number
- 12 bits of BCH error correction
- Two copies, each 6 × 3 modules
Why small codes do not have it
For versions 1 to 6, a reader can work out the version reliably by measuring the code with the finder and timing patterns. In larger codes the modules are small relative to the whole symbol, and a slight measuring error could land on the wrong version, so the standard adds an explicit record.