An international programme of original research measuring how AI systems access, understand, and cite business websites. Every study uses a single versioned, reproducible methodology, so markets and findings can be compared like for like. This page is the map of the whole programme.
What the series is
One methodology, many markets
As discovery shifts from search results to AI-generated answers, whether a business can be found now depends on whether AI systems can reach, understand, and cite it. The Benchmark Series measures that, market by market, using instruments that are frozen and documented before each study runs. Results are published openly, with the underlying methodology versioned so any finding can be traced to the exact instrument that produced it.
The series is published by the Periodic Table of Digital Authority (PTODA), the publisher and steward of the PTODA research methodology. The current generation of studies runs on the PTODA C01 Crawler, a deterministic robots.txt access scanner. Each market is a separate volume; the cross-market analysis synthesises them.
The instrument
PTODA C01 Crawler · v1.5
The C01 Crawler tests how a defined sample of business websites responds to 21 AI user-agents — 14 retrieval-and-citation crawlers (the ones AI search uses to discover and quote content) and 7 training crawlers, reported separately. It separates an observable crawler policy (a decision declared in robots.txt) from infrastructure non-response (an access-denied or unreachable result), and reports the two as distinct layers so neither over-counts the other.
Under the v1.5 five-class graded taxonomy, whole-site exclusion and meaningful restriction are reported separately from the broad binary count. The methodology is fully documented and versioned. Read the C01 Crawler methodology (v1.5) →
Flagship
The cross-market synthesis
C01 · Five-MarketPublished6 September 2026 · v1.5 / v1.5.1
C01 — Global Crawler Access Series: Five-Market Comparative Findings
The current C01 flagship. Australia, the United States, Great Britain, Singapore and India on one frozen evidence base, reported as Coverage → Strict → Meaningful with every denominator shown inline. Meaningful restriction is inclusive of Strict (Whole-site); it is not additional to it. C01 measures crawler access only.
meaningful restriction, of policy-observed domains
2,699
sampled rows
2,652
distinct domains
5
frozen markets
Study 01 · Cross-MarketPublished17 June 2026 · v1.5
AI Crawler Access Across Four Markets: Policy, Infrastructure and Scale
The earlier synthesis of the four published country volumes on one frozen instrument, retained as published: headline rates, the mechanism split (the US denies at the edge; Great Britain and Singapore return passive non-response), the Googlebot-parity finding, and the organisational-scale effect including Singapore's inversion of it.
Five country volumes on the harmonised C01 instrument, listed by market size. For the four earlier volumes the block rates shown are the broad binary indicator, computed on policy-observed domains (readable robots.txt only). Under the v1.5 graded taxonomy these resolve to substantially lower whole-site exclusion and meaningful restriction — see the flagship studies above. The India volume is reported on the graded taxonomy directly.
US Vol 1Published
AI Crawler Access in the United States 2026
The largest market, and the most distinctive mechanism: the US records the series' highest rate of active edge denial.
The fifth and final market of the C01 series, from run R006-IN: 460 organisational domains across ten sectors, and the highest policy-observed coverage in the series. Reported on the v1.5 graded taxonomy rather than the binary indicator used for the four earlier volumes above.
Meaningful restriction is inclusive of Strict (Whole-site); it is not additional to it.
Programme roadmap
In progress, planned and future
AU Vol 2In Progress
Australian Digital Authority Benchmark 2026
A four-dimension authority benchmark (Understand, Trust, Cite, Surface) across 500 domains. The research instrument is in reproducibility validation; publication follows once validation clears.
AU Vol 3 · US Vol 2 · US Vol 3Planned
Authority and citation benchmarks
The four-dimension authority benchmark extended to the US, and AI citation benchmarks correlating digital authority with actual citation frequency across ChatGPT, Claude, Perplexity and Gemini.
New Zealand · EuropeFuture
Additional crawler-access markets
Further country volumes on the same frozen methodology, for like-for-like comparison with the published markets. To be announced.
Roles & attribution: Douglas Lord (researcher and author) · Periodic Table of Digital Authority (publisher and methodology steward) · PTODA C01 Crawler (research instrument) · Digital Dominator Pty Ltd ABN 28 616 931 116 (operating entity). This research publishes aggregate, anonymised findings only — no named individual site results are published.
The Periodic Table of Digital Authority™ (TM 2644497) is a trade mark pending. You may cite findings with attribution. You may not reproduce studies in full or present findings as your own work. Use is subject to the Terms of Use.