GB/T 726-1994
往復式內燃機 旋轉方向、氣缸和氣缸蓋上氣門的標志及直列式內燃機右機、左機和發動機方位的定義
Reciprocating internal combustion engines--Designation of the direction of rotation and of cylinders and valves in cylinder heads and definition of right-hand and left-hand in line engines and locations on an engine
GBT726-1994, GB726-1994