properties /measurement

THE DECLARED COEFFICIENT-OF-FRICTION BAND, as the letter the maker publishes. Every friction part sold in North America is marked on its edge with a two-character SAE J866 code, and the letters are published per part number as well as stamped: Wagner ZD2382 QuickStop Ceramic FF, Bendix SBC2382 Ceramic GG, Bendix CFC2382 Priority One Ceramic FG, Raybestos ATD923C FF, and Bendix's commercial lining range is sold BY the grade — `Silver FF`, `Red GG`. It is the only published number in the whole trade that says how hard the part actually bites, and it separates three real parts for one car that are otherwise identical in form, axle and compound, which is [A13] proved rather than assumed. A GOVERNED TOKEN AND NOT A LITERAL, on [L11]'s recurrence test: `FF` recurs across thousands of parts and every catalogue offers it as a filter, which is the same reading that made `thread_size` a token at b153. STORED AS ONE LETTER PER CONDITION, cardinality many with a required `friction_grade_condition` — never as the two-letter string, which would pack two measurements into one value. The letter is a BAND and not a point (F is anything over 0.35 up to 0.45), which is the pool's standing bounds problem reached from a fourth trade; nothing here can state the nominal coefficient EBC publishes as 0.5, and that is recorded as a follow-up rather than papered over.