How do you read the inverted triangle mark engraved inside the rice pot?

When you open the lid of the Oigen Foundry rice pot, you can see a small inverted triangle (▼) mark engraved on the dark cast iron inner wall^[1]. It is a marker placed so that you can easily gauge the water level according to the amount of rice you are preparing to cook, even without a separate measuring cup.

The reading method is simple. If you have put in 1 gou of rice, align the water with the pointed bottom tip of the inverted triangle, and if you have put in 2 gou, pour water aligned with the flat top line of the mark^[2]. It is a pot that holds up to 2 gou, or 1.2L in volume, making it suitable for cooking 1 to 2 servings of rice^[3].

Although it is a heavy cast iron pot weighing 2.8kg^[4], it can be used widely not only on gas flame and radiant cooktops, but also on induction and in the oven, making it convenient to cook rice without being restricted by heat sources^[5]. However, since it cannot be put in the microwave or dishwasher, care must be taken when handling it^[6].

hmmm, instead of engraving several long graduation lines on the inside, it neatly wraps up two levels of water height with the top and bottom edges of a small symbol.