Architectural tier is determined by the deployment, not by the underlying software

The tier at which a dataset effectively exists is determined not only by the infrastructure available to the researcher but also by the way that infrastructure is used. A Tier 3 protocol deployed in a centralized configuration delivers Tier 1 resilience, because the distributed properties of the protocol remain latent when only one copy is maintained.

GitHub illustrates the pattern. GitHub hosts 630 million repositories and serves 180 million developers (S-0024). Git is a distributed protocol; GitHub is a single commercial platform operated by a single company subject to a single country's legal regime. In July 2019, GitHub blocked developers in Iran, Syria, Crimea, Cuba, and North Korea from accessing their own repositories, citing United States export controls. When affected developers requested copies of their disabled repositories, the platform responded that it was "not legally able to send an export of the disabled repository content" (S-0025, S-0025a).

Developers who had maintained local clones retained every commit, branch, and line of code. Developers who had relied exclusively on GitHub lost access to their own work.

The underlying protocol supported Tier 3 resilience; the usage pattern delivered Tier 1 exposure. A researcher who deposits a dataset in a single repository and moves on is operating under the same pattern. The infrastructure may support distribution, but a single copy in a single organizational context is Tier 1 regardless of what the underlying technology makes possible.

The architectural tier is a property of the deployment, not of the software. Recommendation 6 (R6) makes the corresponding operational point at the laboratory level: maintain at least one local clone and one content-addressed copy of every research dataset.