Boundaries of the Chang’e-6 unit with the exclusion of secondary crater fields. Our mapping boundary (blue) generally matches the largest consensus region among previous definitions of the boundary of the Chang’e-6 unit. The boundary of Xu et al. (2024) was taken from Zeng et al. (2023, a candidate landing region of the Chang’e-6 mission, named F; the flame red), which is a subregion of the boundary of Pasckert et al. (2018, not shown for clarity), and the boundary of Yue et al. (2024) is a little larger. The largest unit boundary (Haruyama et al. 2009; Pasckert et al. 2018; Yue et al. 2024) is not shown for clarity.