Constant MEMORY_WRITE_ELEMENT_LABEL 

pub const MEMORY_WRITE_ELEMENT_LABEL: u8 = _; // 4u8

Unique label when r/w=0 and e/w=0, computed as the full chiplet selector with the bits reversed, plus one. selector = [1, 1, 0 | 0, 0], flag = rev(selector) + 1 = [0, 0 | 0, 1, 1] + 1 = 4