Using Max Path as the primary score for grouping as we do here, the Easy category could also include brackets of 3-4 segments if they used only ideal Cys ligation junctions in a convergent order (in our E. coli ribosome set, Cys are sparse and no brackets of this description are found). In our judgment, it would be fair to group these ideal all-Cys brackets in the Easy category. As more segments are introduced, however, special attention must be paid to initial quality of starting segments to avoid accumulating impurities in the product. Even "easy" brackets, therefore, require close assessment of initial segments, the full ligation path, and an individual lab's capabilities. "Medium" Proteins (Max Path 3-4) About half of the ribosome (31 proteins) can be characterized by brackets of 2-4 segments with slightly sub-optimal ligation paths. In these proteins, even the preferred ligation strategy faces at least one challenge, such as multiple A ligations requiring simultaneous desulfurization (L3, L4, L7, L9, L18, L20, L35, S5, S10, S16), unavoidable poor thioesters (IF-1, L15, L16, L21, L25, S6, S7, S9, S19), a combination of A and C sites constraining possible ligation order (L10, L11, L14, L17, S11, S13, S14), or all A ligations with internal C in some segments necessitating Acm protection (L5, L6, L10, L28, L35, S12, S18).