Light curve and model for OGLE-2018-BLG-1647. The anomaly is a bump centered at 8369.2. The planetary interpretation is favored over the binary-source model by Δχ² = χ²(1L2S) − χ²(2L1S) = 28. While both close and wide caustic structures are illustrated, the wide solution is decisively favored by Δχ² = 17. Nevertheless, this (albeit broken) degeneracy proved to be the “Rosetta Stone” for the unification of the close/wide and inner-outer degeneracies (see Sects. 3.1 and 3.4).