{"claim":"An index keyed on identification numbers silently loses every material the 172.101 table designates Forbidden, because the table gives them no identification number.","counts":{"hmt_entries":3293,"forbidden_entries":256,"forbidden_carrying_an_identification_number":0,"recoverable_by_id_keyed_lookup":0,"recoverable_by_this_index":256},"live_demonstration":{"material":"Ammonium chlorate","identification_number":null,"hazard_class_column_3":"Forbidden","lookup_by_identification_number":"impossible: the regulation assigns this material no identification number","lookup_by_name_in_this_index":"1 result, designated Forbidden","consequence":"A tool that resolves materials only by identification number returns nothing here, and an empty result is indistinguishable from 'not regulated'."},"governing_clauses":[{"section":"49 CFR 173.21(a)","text":"Materials that are designated \"Forbidden\" in Column 3 of the § 172.101 table."}],"how_to_check_this_yourself":{"step_1":"Open https://www.ecfr.gov/api/versioner/v1/full/2026-08-27/title-49.xml?part=172&section=172.101","step_2":"Find the 172.101 Hazardous Materials Table and search column 3 for the word Forbidden.","step_3":"Observe that column 4, Identification Numbers, is empty on every one of those rows.","step_4":"Compare the count to forbidden_entries above.","offline_alternative":"git clone the repository, then npm ci && npm run verify:data. No key, no account, no network."},"names":["Acetyl acetone peroxide with more than 9 percent by mass active oxygen","Acetyl benzoyl peroxide, solid, or with more than 40 percent in solution","Acetyl cyclohexanesulfonyl peroxide, with more than 82 percent wetted with less than 12 percent water","Acetyl peroxide, solid, or with more than 25 percent in solution","Acetylene (liquefied)","Acetylene silver nitrate","Acetylene, solvent free","Aluminum dross, wet or hot"],"names_note":"first 8; append ?full=1 for all 256","provenance":{"ecfr_snapshot":"2026-08-27","title_49_latest_amended_on":"2026-08-19","title_49_up_to_date_as_of":"2026-08-27","source":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-27/title-49.xml?part=172&section=172.101","legal_status":"The eCFR is an editorial compilation and is not the official legal edition of the CFR. 49 CFR is a work of the United States Government, not subject to copyright under 17 U.S.C. 105. This is not legal advice."}}