The parts of the valve do not understand
Are the two forks of the cutaway section? That's flat.
The drawing rules for some detailed structures in mechanical drawing:When a small plane of an instrument is not adequately represented in a graph, it can be represented by a flat sign (two thin solid lines intersecting).Two visible square planar graph in your local section after the hole is the case.
Representation plane. (two intersecting lines determine a plane)
