Distribution of log(gf) vs. Δ log(gf) (NIST–BRASS) for the NIST (2016) and BRASS (2012) non-parametric cross-match. For clarity and consistency a small number of transitions with |Δlog(gf)| > 2 have been excluded. In some extreme cases these Δlog(gf) values can be as large as Δlog(gf)  ± 2 dex. When compared with Figs. 1 and 3 we find that NIST is weighted more towards stronger transitions than SpectroWeb or VALD, no doubt due to the experimental provenience of NIST transitions.