grading scale
also called which scale
Which published scale a `viscosity_grade` is a place on — SAE J300, SAE J306, NLGI or ISO 3448. It is STORED and never derived, and the ground is [L10]: the engine reads only CODES and codes are opaque — the strings live in a lexicalization layer the logic never reads — so nothing in the graph tells a consumer that `val_ViscosityGrades_nlgi_2` sits on a consistency scale and `val_ViscosityGrades_iso_vg_46` on a kinematic one. That is precisely why the live pool carries `size_system` as its own property even though `Sizes` already holds scale-bearing values (`val_Sizes_eu_42`, `val_Sizes_uk_8`) beside bare ones (`val_Sizes_42`); this slot is that precedent. The printed designations really do overlap across scales — ISO 3448 defines VG 2, 3 and 5 while NLGI defines 2, 3 and 5, meaning opposite things — but that collision is NOT the argument, because the minted codes are already distinct; the argument is opacity. The harm without it is real all the same: an 80W-90 gear oil on J306 is about as thick as an SAE 50 engine oil on J300, so a comparison that does not know the scale returns a wrong answer. The qualifier of a graded classification, the b153 precedent where `filtration_rating` carries its basis and standard.
Grading scale is answered with one word chosen from the viscosity grading scales list — the same word shared across every product that uses it.
It is a qualifier of viscosity grade — it has meaning only inside a viscosity grade statement, never on its own. It belongs with viscosity grade to measurement — its measurable, physical facts.
It is answered inside every viscosity grade statement, not as a standalone question on a kind.
Answered inside every viscosity grade statement — not a standalone slot on any kind.